eggs sound difficult, unless you boil them. but they would break. you could make it ahead of time. stored in cooler.
are these ideas mostly for you?
pouches of salmon/tuna.
trail mix- easy to make healthier version for you. gives great energy for hikes.
grilled chicken, fish, or other meat.
tortillas work in place of bread
are you carrying the food too? well i guess not with a cooler. you have more options if you don't have to carry it.