Walking Tacos - Brown hamburg at home and freeze. At state park, heat hamburger and a packet of taco seasoning mix(only adds water to make)let it warm up. Get a bag of Doritos (single serve bags you can dump everything right in - I use the big bags and plates) lettuce, tomatoes, cheese, taco sauce, sour cream and anything else you would like.
Hamburger Helper, Tuna Helper, Chicken Helper all can be made in a skillet.
Omelets can be made in a ziplock bag and boiled in water to cook. Just add whatever you want to the egg mixture first.