has just about every idea ever made, even if you don't use their box. i love my thermos funtainer [10 oz and keeps things hot or cold for 5 hours and when i have to eat lunch late, i'll put my yogurt in it, add frozen berries and it's too frozen to eat for 5-6 hours]. having a well insulated lunch tote and cold packs are going to be your best bet.
plan your meals by doing more lunchlike things [pbj] for dinner and going fresher and perishable for lunch [since it won't sit as long]. so yogurt or cheese might be a lunch item, but a snack of carrots would be fine with dinner.
also, look to what shelf stable things you can find. cup of soup has come a long way, particularly the dr macdougall's, nile and health valley brands. they have lentil curry, potato and leek, black bean [13 g of fiber in that cup of soup!], miso and several others. all you need is hot water, which should be available anywhere with coffee. thai kitchen and simply asia also make noodle carts and other add water and microwave things.
speaking of microwaves, see if your school has some sort of off campus student lounge. mine did and there were couches and a mini kitchen like all the dorms had. so you had hot water, a fridge and freezer and space to do a little prep and cleanup. if you have access to one of these places that would open up a lot more options for you.
-google first. ask questions later.