Take a cookie sheet, cover it in aluminum foil, lay out the family pack of chicken breasts. Season to taste. Cover with another sheet of aluminum foil, bake at 300F for a while, turn up the temperature to 450F, take off the foil and brown for 5-10 minutes on a side.
If you do not want the chicken to set in what will mostly be water, move to a paper towel and let it dry there. Individually wrap in cello.
If your trips are long, long long, freeze a few pieces, use those as 'Ice' and have cold chicken (not frozen) on top to be your first eating.
Do you like spinach - not the canned stuff that has been cooked to slime, the real leaves. If so then wrap a breast with spinach leaves. You can add things like a wee bit of good cheese, rice, etc. Hold the leaves together with a bit of tooth pick. If you want you can steam the whole packet a few minute to partially cook the spinach. Wrap and cool in the ice box. They make for nice 'tidy' sandwiches, low carb if you are not wanting bread.
Hard boiled eggs are good, instead of just storing them in the shell for a road trip, peel them first, put in a hard bowl to keep them from being crushed.
I tend to eat a lot more fruit and veg than meats and sandwiches on long drives. Fruit that doesn't need to be peeled is easy to eat, and do not need to be chilled.