For years, my wife and I felt like expert road trippers.
We keep things simple and plan to eat out a little along the way.
We take a loaf of bread and a jar of peanut butter for sandwiches, boxed snack cakes/fried pies and such for snacks, a couple of bags of chips, and a cooler full of sodas, gatorades, and waters.
None of that stuff needs to be refrigerated, so there's no worries of spoilage or lunch meat getting soggy.
We even have a method on how to place everything so the front seat passenger can reach it all.
We munch on that stuff whenever wherever, then we stop someplace decent for dinner.
It helps keep our average speed up too, since we can eat while we drive and try to take restroom breaks only at our gas stops.
On really long trips, like our Anchorage to Dallas trip, I'd keep a box of Capri Sun drinks between the driver's seat and the driver's door of our Jeep.
That way, when it was 2:00 in the morning, and I was the only one awake, I could grab a quick drink without disturbing my wife while she slept.