It doesn't take that much effort to eat right on the road. It is important to not over eat and to have a balanced diet. Stay away from the fast food. Eating at Subway is probably more healthy than eating at McDonald's as long as you get veggies on your sandwich. Rather than buying a 12" sub, buy a 6" or only eat half of the 12" and stick the other half in the cooler to eat later.
When I am on the road, I try to eat vegetables at least once per day. I often have an omelet for breakfast and have the restaurant substitute fruit for potatoes. I also tend to drink more water with meals rather than a soft drink or tea, although tea can be good for you. Water is best. I never eat potato chips on the road and rarely at home. Much of eating right is common sense.