Most RVs come from the factory with at least one outside light near the entrance. They are usually fixtures with a single incandescent bulb, but LEDs are becoming more popular. Some may have integrated switches so you can turn them on as needed from outside the vehicle, like for finding the right key and the key hole in the dark and finding the step so you don't fall flat on your face! If your RV doesn't have a convenient porch light, one can be added fairly easily. You will want to mount it on the side of the door where the handle is. You can usually mount the light at the same level as the bottom shelf of an inside cabinet. This allows you to tap into power already supplied to the under cabinet lights and to hide the new wire you run to the outside for the porch light. The bottom shelves of most RV cabinets are hollow. You gain access to the hollow space by prying up the top of the shelf inside the cabinet. Take care not to damage the paneling, which is fairly thin and easily crunched. Once you have the panel off you can see where to hook up the wiring for your new light. You can drill a hole through the back of the hollow space inside the shelf all the way through the outside skin to run your wire. Most porch lights are designed for surface installation. You will want to run a strip of butyl tape ("dum dum" tape) around the outside edge of the fixture before you screw it to the outside wall. A bead of Dap or silicone caulk where it contacts the wall will provide further protection once it is fully installed. Also squirt some sealer into the hole around the wire. This both prevents air and water intrusion and helps keep the wire from chafing on the edges of the hole.
RV porch lights are ideal candidates for conversion to LEDs. You don't need a lot of focused light like you would on a work area for reading and having LEDS bulbs significantly reduces the battery drain if the light is left on for a long time. A guest once left the light on in our RV bathroom (standard incandescent bulb) and the coach battery was dead in just a few hours. I've used LED step lights for several years now, leaving them on day and night for days at a time without running down the batteries. Converting most lights to LEDs is as simple as changing the bulb just get the right size to replace the current incandescent bulb. LED equivalent sized bulbs may come in a variety of "colors" and intensity. Some may have a soft, yellowish tint, others may be bright white. Be sure to get ones that will work the way you want them to for each application.
The porch lights on some RVs are controlled by a switch inside the RV. This makes it convenient to turn off the lights at bedtime, especially in bad weather, but it leaves you in the dark when you approach the unit at night unless you leave the light on while you're away. A really convenient and fairly inexpensive (under $20) solution to this problem is to install a battery operated, motion sensor LED security light near the door. You can also get solar powered versions, but be aware that installing them in the shade of an awning (which may shade the solar panel even when the awning is rolled up) may reduce the effectiveness of the solar capability. LEDs draw little power so you shouldn't have to change the batteries in a battery powered unit very often. There are hard wired 12-volt versions, but they require running power from somewhere inside the vehicle whereas the battery powered lights can be easily mounted anywhere and are self contained so you don't have to drill any extra holes in the skin of the RV. They don't have to be very bright or provide the kind of broad coverage you might want for other lights that you would use to illuminate the campsite or even the patio area for night time activities They just need to give you enough light to find the right key and the key hole and to make it so you can see the step. Once you have the door open you can always turn on the regular porch light if you need things brighter. A motion sensor light is a very friendly "welcome home" when you approach your rig after dark and can provide a level of security by illuminating the area when someone else approaches. Would-be burglars are often deterred by lighting that might reveal their activities and identity and send them seeking a more secluded target. I found a suitable light on sale at Harbor Freight. The bracket installed easily with 2 screws (provided) and the fixture can be quickly removed from the bracket to avoid losing it while traveling or having branches knock it off in close quarters. Having that light turn on to greet us as we approach the door a night feels very friendly and is very convenient. If you want to leave your standard porch light on while you're away, consider changing the incandescent bulb to an LED replacement which will draw considerably less current from your batteries. An easy, convenient, and inexpensive way to add outside LED lighting is via "tap lights". These fixtures are normally designed for use in closets and cabinets so you'll probably want to mount them so you can remove them in bad weather or while you're on the road. I've even found some at my local Dollar Tree, making them VERY inexpensive. They run on 3 AAA batteries, which last a long time with the LEDs. If you're not worried about weather you can stick them to the side of your RV near your door with double-sticky tape that is usually included. Substitute Velcro for the double-sticky tape if you want to make them removable.
You may find it useful to install outside lighting at other locations besides the entrance, and only a few RVs have secondary lighting as original equipment. You can use the above procedure to install outside lights just about anywhere you find it useful. Some typical places are on the front of trailers to assist in connecting up to the tow vehicle in the dark, near water fill and other utility locations, and near an outside shower. Extra lights under the awning can make outdoor might time activities more practical. 12- volt lights for general camp ground illumination can usually be tapped into existing wiring for under cabinet lights as described in the first paragraph above making installation fairly simple. Most RVs have at least one 120 volt outlet somewhere on the outside of the rig so it is convenient to use under the awning. You can usually run a light weight extension cord from this outlet to a string of patio lights attached to the awning or to other area lights, assuming you have 120 volt power from hookups, generator, or inverter. I prefer to use 12 volt lighting rather than run 120 volt lighting from an inverter. Incandescent bulbs, being essentially a dead short, draw a lot of current and could suck down batteries pretty quickly. 120 volt LED bulbs would help mitigate this problem.
Lighting on the front of a trailer can illuminate the hitch and make hooking up or disconnecting at night a whole lot easier and safer. Once again you can often connect to existing wiring inside the bottom shelf of a front cabinet. I like to use lights with a built in switch so I can turn them on and off as needed without entering the trailer.
A few RVs have extra outside lighting but this is usually something that is left to the owner to install since individual needs can vary dramatically. I
added a couple of high intensity flood lights salvaged from an ambulance to
my enclosed motorcycle trailer, one at the rear over the ramp door and
one on the side under the awning so I have good illumination for after
dark dirt bike repairs. Such lights would not be necessary or
appropriate for all users. For convenience I hooked them up using residential style 3-way switches, including one waterproof exterior switch. The biggest downside I've found with these lights is replacing the bubs. They are very specialized, hard to find, and rather expensive but, fortunately, are very well made and designed for years of high stress use. If you are inclined to cook on the outside
BBQ you might find it useful to install an extra exterior light over the
area where you will be cooking. If you like to play games on the
"patio" in the evenings you might benefit from various kinds of awning lights. If you have an outside shower you might want a light there in case you need to rinse off after dark. Extra porch lights along the side of your RV can provide additional campground illumination. I have a 500-watt Halogen flood light I can mount on my RV ladder when I need to light up a lot of campground, but big lights like that often intrude on surrounding camp sites so be careful about using them. My 40' Holiday Rambler had a pair of bright 120 volt lights on the curb side that did a good job of illuminating our campsite. I added the sockets and bulbs from a pair of 12-volt, 55 watt halogen driving lights in the same housings so I didn't have to run the generator just to light up my campsite. The 120 lights could still be used when the generator was running or I was connected to shore power.
Having lights that illuminate the steps on your RV can be really helpful at night. Some fancy rigs with automatic electric steps have automatic lights. If your rig doesn't have lights you can add them pretty easily. I did mine using an amber LED clearance light. I have run it continuously throughout a 3-day weekend 24 hours a day, without running down the battery. You will need to find a source to connect the 12 volt positive line to and a good metal ground. You can usually ground it someplace on the step. Put the switch in a convenient place near the door. If you want to put it outside so you can turn it on when come home to your RV late at night be sure to use a waterproof switch. I like to use an illuminated switch that indicates when the light is on.
Installing wall mounted lights to illuminate outside cabinets is pretty much counter productive. The light around the open door will just make it seem darker and harder to see inside the cabinet. If you need to see inside cabinets at night and your cabinets are not lighted, it is really easy to install LED "tap" lights. These are small, battery powered lights that attach with double sticky tape and are turned on and off by tapping the lens. Or just use a flashlight. Some of the higher end rigs have automatic lights in the outside cabinets like the ones in the closets. Automatic lights can be added, but it may take some ingenuity to find a way to run the wiring and the switches can be temperamental. Doors that are hinged on top sometimes use mercury switches, which can be difficult to find these days due to the environmental concerns about mercury poisoning. Plunger type switches can be used on just about any door, but getting them properly adjusted can be tricky If just one isn't adjusted right, the draw from an incandescent bulb can drain house batteries in surprisingly short time -- and you probably don't have any way to see if the light is on inside a cabinet. Using LED replacement bulbs is one way to minimize current draw but LED replacements are still fairly expensive: around $10 per bulb for good quality. You can find less expensive LED bulbs on the Internet but reports and personal experience have shown they don't live up to expectations. Users have reported early and frequent failures (one even said NONE of the bulbs in his shipment worked!) and insufficiently bright lighting. All the ones I've tried worked, but I found that incandescent bulbs provided much brighter illumination. I even bought a few of the more expensive LEDs and found that the blue-white light wasn't very appealing and they still failed to match regular bulbs for overall illumination where needed for work or reading . However, the power consumption and the heat generation of LEDs are indeed far less than incandescent bulbs. Using a combination may be the best solution: LEDs where nominal illumination is adequate to save power and incandescents in work areas where you need good lighting to save your eyes. A really easy solution to cabinet lighting, both indoors and outdoors, is an LED "tap light". They typically run on 3 AAA batteries and attach easily with double-sticky tape. Simply tap the lens to turn them on or off.
Light 'em up!