I would not worry a lick about nutrition or fiber for a short trip. Only when you are out for a week or more does a poor choice of food make much difference. Take what you like. Take a deli sandwich (as long as it does not have eggs or mayo that can spoil). Eat extra veggies when you get back home. It is wise to take the same kind of food you regularly eat. Noodles, cheese, jerky, nuts and dried fruit - all good if your system can handle it. Your digestive system may rebel at something entirely different. This is why I do not like freeze dried meals. They taste OK but my belly does not like them. Same with candy bars. I never eat them at home and if I take them backpacking, I get a belly ache.