Not very budget friendly but i found frozen burgers or pizza from your favorite spot are nice when out camping. I warm things up in a large pan with a lid on low heat. Walk away and come back 30 or 60 mins later. Nice knowing it wont burn if out talking with friends. Come back to the trailer for a beer and you have a toasty in&out burger ready to eat. The lettuce and tomato are not all that happy being frozen and then reheated. If you let the buns get nice and toasty it sorta balances out the potentially soggy inside part of the bun.
edit: in terms of bulk you would already be going to the restaurant. Buy more on purpose to freeze. A frozen in and out burger wrapped in foil in the fridge is like a block of gold when out camping!!!
