For trips around 300~ miles, I pack sliced cheese, italian salami slices, crackers, or sandwiches, fresh fruit, olives. Feels like having a picnic in the car since we don't stop to eat food. I'm a big fan of fresh fruit-it keeps pretty well, doesn't necessarily require refrigeration (aka a cooler), low environmental impact, and healthy. Also consider cut fruit mixed together in one large container (watermelon, strawberries, pineapple). This could be served with bowls or cups for individuals.