I wouldn't be eating a lot of fruit if I was doing a lot of sitting. I know a guy that drives and I think he mostly eats out of cans. He'll have, like, a can of salmon and a couple cans of veggies. Yea, not that exciting but he's sick if he eats outside his diet of mostly meat and veggies. Pemmican, beef jerky, veggie chips (dehydrated yellow squash, for example, is quite nice, or fry yourself some veggie chips) are all easy to keep. Do you have any kind of refrigeration or are you grabbing sandwiches (no bread I assume) on the go? You can always go in to a walmart and buy fresh vegetables, lunch meat (there are some meats there without nitrates/nitrites, at least at ours there are). Kefir and fermented veggies, you could start them when you leave somewhere, kefir takes a good day to make, fermented veggies can go for several days to reach peak tastiness.