I suggest carrying CousCous. For those unfamiliar with CousCous, it is a partially precooked pasta like product originally from Morocco or thereabouts. Near East brand is available in several flavors. When you mix it with equal parts of boiling water, let it sit for 10-15 minutes, it will make a satisfying carb dish. If you don't carry a stove, I suggest you buy a medium tea form a fast food place, they will probably give you a paper cup with hot water and a tea bag and you can use the hot water for couscous, hopefully it is hot enough - near boiling.

I also have a no cook recipe for beans. A can of your favorite beans, e.g., chick peas, black beans, cannellini, etc, a can of a veg. e.g., corn, green beans, peas, etc. some fresh onion, salt, pepper, lime juice and you can eat it alone or scoop it with chips. You may end up with a lot and may want to save unmixed beans for later.

Some dry uncooked beans, e.g., chick peas and mung beans (you can find mung beans in Asian markets) can be eaten raw after first soaking them in water for a few hours. It is a good snack too, fills you up very quickly.