I know a lot of OTR drivers who have the same problem. Not only is most truck stop food deep fried or covered in gravy, it certainly is not cheap. What a few truckers I've known have done is to stop at a grocery store and stock up on fresh fruits and veggies.
It takes planning to eat healthy. I can't count how many times I found myself hungry with no food in the house and my only option being a fast food joint.
If you have a crock pot or similar device in your truck, then you can certainly find healthy cooking books for those pieces of equipment. Good luck with this and Go Big Red!
I live to eat. I shall die with an entire cheesecake in my tummy, surrounded by empty beer bottles and soda cans, with a slice of cold pizza still in my hand. Oh death, where is thy sting?