I'd say plan for both, outside and inside. The heat and smell objection I don't get really, I've been doing it for 50+ years. Inside open a window, use a fan open the vents, if ya got air, turn it on. As to smells, I don't cook fish or liver and onions inside, but coffee smells good, turkey bacon is pretty good, hard boiled eggs for a sandwich or salad, don't smell, neither does warming up corn or veggies, seems you'd plan the meal around the environment. So, if it's cussing rain, blowing blizzards outside, you still get a hot meal.
Other meals, steaks, chops, fish, burgers.....all the poppy smelly stuff goes outside on the grill.
If I'm on high ground, not in the mud, I'll cook outside with a tarp or awning, that's great in a light rain.
And, the idea of space taken up.......hmmmm? "Space" is what you're hauling between the wheels, inside, outside, under or over it doesn't matter, you're still hauling the kitchen(s) and all the infrastructure and equipment to use it.
The trip dictates the kitchen needed, might try to think of being more flexible. Yes, it might mean that you end up with 3 or 4 camp stoves, but my little backpacker isn't going to cut if for 4 people with a truck and trailer. Might be fine for float trips, but I'll probably take the 2 burner. My 3 burner is best for longer stays with more folks and the grill can go too.
The "infrastructure" that's the chuck box, the material used to make the doors, table, shelves, compartments, drawers, heavy duty slides, racks and containers......how much does all that stuff weigh? Is it really needed? A shoe bag hanging on a door doesn't weigh much nor does it take up much space. A large canvas bag makes a fine sink. An oven rack makes a shelf, small table or a grill on a fire. Stacking food containers after use don't really take up more space, the left over beans are in one container and that container is in 3 other empty containers, still in the fridge or cooler.
I'f I want a class A motor home, I'll take the stainless fridge/freezer and granite tops with rosewood cabinets. Otherwise, the kitchen needed for the trip is selected, space available, weather, cooking what menu where and when. Inside and outside.
Versatility is key, IMO.
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