Most of our traveling involves a long hard trail ride, away from the truck and icebox. In an effort to have usable energy without that sugar crash we increased proteins that still have moisture in them yet can go all day without refrigeration in the camelback. If it's hot out, some items get partially frozen and thaw by lunch.
*Rice balls (Japanese sticky rice seasoned, filled with smoked salmon, pulled pork, or other leftover/canned concoction) these are the ancient Japanese art of the energy bar. I've Americanized these fillings, and wrap them individually in saran wrap.
*Leftover BBQ chicken pieces/slices or steak slices. (seasoned with Pappy's dry rub for BBQ, presliced, into serving/snack baggies, eating cold with or without sauce.)
*hard boiled eggs still in the shell (with tiny packets of salt/pepper saved from in & out burger)
*leftover cold pizza, each serving individually wrapped.
*foil packets of tuna or smoked salmon (we always have one or two for emergency food)
*pickles or other fermented foods travel well.
*hardy traveling fruits: apple, clementines, etc
*salami or deli meat, cheese slices, and wheat thins
*sweet bread 'sandwiches' (sliced bandana, pumpkin, or zucchini quick bread, with cream cheese or 'better than cream cheese' generously spread between slices)
*a PB&J on sourdough or wholegrain (resists crushing better) is also included as 'insurance' incase the day goes long. Each is wrapped in one or two paper towels before put into the zip locks baggie - to contain any oozy mess and keep hands cleaner. I can also label the paper towel with a sharpie for contents or by initials. e.g. low sugar peach... His/hers. I don't mind if these don't get eaten and thrown out, they are insurance against unexpected delays mechanical breakdown /injury/navigation errors/ challenging weather or trail conditions. They are better assimilated energy than the 3 year old Luna bar sitting in the bottom of the backpack.
We've reduced the nuts/granola/dried fruit/power bar snacks since they can be heavy on the digestion system and pull water from the body (not good when traveling).
Small chocolates (think Halloween sizes) for mental health or end of meal palate cleanser.
In the icebox can be items with containers:
*jello w/ fruit in bottom (full suger kinds stay fresher longer than reduced sugar), Chocolate (tofu) Pudding, almond milk tapioca. (not all the same day)
*cold deli salads, either homemade or store bought: pasta, salads, 3+ bean salad, chicken curry(not all equal), potato salad, Hawaiian chicken salad, tuna(or rabbit) salad, egg salad. The last three can be eaten with crackers, sans utensils.
*Bento box of veggies and dip in manageable secure-lidded box, items mostly separated by silicon cupcake holders. Veggies: carrot sticks, Cucumber slices, jicama sticks, sliced bell peppers, radishes, etc. Many slices are used with a
Dip: of hummus or Ranch dressing in a small container. Or guacamole with chips.
Delicate fruits go in the Bento - berries, grapes, etc.
Search Google for 'Bento lunches' for ideas. You'll have to look beyond some creative food art for ingredient ideas.