If you have a self-contained motorhome or travel trailer chances are it has an oven. Many RVs these days include a microwave or microwave/convection combo oven and many have a range with a gas oven. If you're tent camping, or your RV doesn't have an oven (some RVs have only "cook tops" with 2 - 4 burners and no oven), you may have to seek other options. Tear drop trailers usually have just a one-burner portable butane or propane stove to be used in the rear "kitchen" or you just use your own Coleman stove. The gas oven in an RV will function pretty much like the one at home, but it's smaller size may limit how much food you can prepare at one time. For example, you may have to bake each layer of a cake by itself, instead of doing 2 or more at a time like you might do at home. The smaller size may also mean the heat sources are closer to the shelves which may affect baking temperatures and times. If the bottom burns before the whole thing is cooked you either need to use a higher shelf or turn down the heat and bake longer.
Microwave ovens are wonderful conveniences in RVs or even tent camping if you have power. You'll need shore power from a campground pedestal or an on board or portable generator or an inverter and strong battery bank. Microwave ovens in RVs are often installed at eye level. Be careful removing food from the microwave. It can be VERY hot -- hot enough to create 2nd degree burns if it spills on your skin! That is one reason microwave instructions on many foods say to let it set for 2 minutes before serving. The other reason is to let the food continue to cook, so don't be in too big a hurry to pull it out of the oven! Having a convection microwave may eliminate the need for a conventional gas oven.
But what do you do when your only option is cooking on a Coleman stove or a campfire? Coleman stoves typically have 2 or 3 burners but no oven. Campfires are just a big batch of flames or, if you are patient enough, coals. Sometimes you have have a grill over a campfire to support cooking devices.
The Coleman Camp Oven has been a traditional camping oven solution for camp stove users for years. It is light weight, folds to 12"x12"x2" for storage and transport, and expands to 12"x12"x12" for use on a 2 or 3 burner gas stove or an RV cook top. You might even be able to use it on a campfire if you have a grill or grid to set it on. It is an easy way to bake biscuits, rolls, entrees, and pizza in camp. You might even be able to do bread, brownies, and cakes once you've gotten the hang of using it. Since it sits on top of your gas stove, it is somewhat affected by wind if you're using it outside. Using a wind guard around the stove will improve performance on windy days. Expect to pay $25-50 for a brand new oven or watch garage sales, thrift stores, ebay, etc to get a bargain on a used one. Unless they have been badly bent or otherwise abused, there isn't much that can go wrong with them. You might have to give it a good cleaning.
For a more home-like solution, Camp Chef and Coleman both sell a portable outdoor range and oven for about $200 -$300. I've seen used ones offered on the 'Net for around $160. This is scaled down version of your kitchen stove at home, with 2 gas burners on top and an oven with 2 racks. It even looks like a miniature stainless steel kitchen stand alone range. Here is a link to the Camp Chef Portable Oven. so you can get an idea of what they are like. Pretty luxurious. It comes equipped to run on a standard 1 lb propane bottle but can be adapted to use larger propane cylinders. This also makes an excellent survival stove for emergencies. Since the oven is not dependent on an outside heat source, it isn't affected by wind but you may still need a wind guard on the top burners when the breeze picks up. If it you have the budget for it, this is an excellent way to bring along complete cooking facilities for tent camping or for use in any RV that doesn't have a functional range and oven and as a home emergency stove. You might even find it less expensive and more convenient than replacing an RV range and oven if yours has failed. Just be sure to provide adequate ventilation anytime you use it in an enclosed space.
Dutch ovens are always a good option when camping. A Dutch oven is simply a cast iron (or sometimes heavy aluminum) pot with a sturdy lid. They can be used on your gas stove or in the campfire or heated with charcoal briquettes. You can cook just about anything in a Dutch oven but you will usually want to seek out special Dutch oven recipes for best results. They are very adaptable and can cook almost anything from soups and stews, to one-pot main dishes, to breads and desserts. It is common to combine meat, potatoes, and other veggies together and let them simmer for a few hours for a really easy, tender, tasty, meal. I think of it as a pioneer crock pot. A favorite Dutch oven dessert is a kind of "dump cake". Check the Internet for specific recipes but the general idea is to dump a can of your favorite fruit or pie filling into the bottom of the pan, dump a box of cake mix on top of it, and bake. Always line your Dutch ovens with aluminum foil to make cleanup easier, especially when cooking sticky desserts. Dutch ovens are perfect for cooking foods that benefit from long simmering, like chili, stew, chicken, and pot roast. Think of them as kind of a pioneer crock pot. Set up your Dutch oven before you begin your recreational activities for the day and by dinner time you'll have a hot and tasty meal waiting to be ladled up. You typically need charcoal underneath and on the lid. Figure on putting one briquette on top for each inch of diameter of the Dutch oven. A lid lifter is a handy accessory or use a pair of Channel-lok style slip-joint pliers. The cast in loop on the lid gets very hot.
Not exactly an oven but kind of related are camp toasters. Typically they consist of steel disk with a wire frame on top that holds 4 slices of bread for toasting. They are inexpensive (usually under $5) and fold flat for easy transport and storage. You need to keep a close eye on your toast to make sure it doesn't burn and you'll need to turn the toast to cook both sides, but it makes really good toast on a Coleman stove, an RV range or even a campfire.
An alternate way, with a pioneer flair, to cook breads etc is to make the dough thick and wrap it on a stick and cook it over an open flame (campfire or camp stove) to make campfire twist bread. A forked stick works best. Or heat some non-porous flat rocks in your fire until water sizzles when dropped on them and drop the dough right on the rocks. You might even try making a stone oven of flat rocks and put your dough in there for baking. Ash cakes can be cooked by dropping dough directly on hot coals. It is surprising how little the coals stick to the bread but be sure to brush the ashes off the bottom before you eat them!
Solar ovens are a nice eco-friendly way to go. And using them is easy on your pocketbook although ready-made solar ovens can be a little pricey. However, you can find numerous plans for building your own solar oven on the Internet. Usually all you need is some cardboard and some aluminum foil. Your only fuel is sunlight. Not going to do much baking on rainy days, but solar ovens are an interesting and economical option for fair weather, and, after all, don't we all try to do most of our camping in fair weather?
If you are always camping with full hookups or have a generator, you could consider bringing along microwave or toaster ovens to make meals in camp more convenient even when tent camping. With today's quiet, light weight generators, they're even feasible for tent camping. Many RVs have built in microwaves. If yours does not, you can probably add one or just bring along a small model that can sit on the counter (see my post on Replacing or Installing a Microwave Oven for additional details).
Campfire pizza. You can make campfire pizza in a frying pan. A cast iron skillet is the best choice for direct use on the campfire, but you could make pizza in a regular frying pan on your camp stove or, if you are careful, even on the campfire. Dutch ovens are another option for making pizza in camp. I have seen pizza ovens advertised for campfire use but to me they were way to expensive and way to cumbersome for use in camp. Might be worth it if you were selling pizza in camp!
Military field cookers might be an option for car camping, but from what I've learned about them, they're large and heavy to haul around and use a LOT of propane -- IF you can find the right regulators to make them work properly and that seems to be a common problem. I've heard they often have regulators and orifices that aren't compatible with civilian propane systems. Keep in mind they're literally designed to feed an army. Individual military equipment is worth looking into for camping, but unit level stuff is mostly designed to be transported in 2 1/2 to 5 ton trucks and feed hundreds of soldiers. Probably too big, too heavy, and too expensive for most of us and way overkill unless you have a really big family or plan to frequently feed the whole campground on a regular basis.
Bake up!