Box of mac n cheese
Cook n dehydrate the pasta
put dry ingredients in correct amounts in ziploc bag.
on the trip, add water to the pasta and rehydrate, adding in extra for the powdered ingredients to turn to sauce. Cut up a cheddar cheese stick for extra punch. Add rehydrated peas, tuna, chicken, whatever you like.
If you don't like dehydrating - leave the pasta at home and sub in couscous, which is already a just add water food.
Whole foods has a variety of packets of cheese sauce, some of them vegan. Not all of them taste like cheese.
For a cheesy substitute, shredded hard cheeses melted over the top of the pasta - hard cheese packs well.