In fall of '09, I drove from NC to to AZ & return mostly to see the Petrified Forest & Meteor Crater. I was a little pressed for time, so it was a 'quick' trip (20 nights, IIRC). The Grand Canyon and other stuff along the way were just added extras (yep, I know my interests are odd). I overnighted in rest areas & truck stops except for two nights drycamping in the National Forest near GCNP.
I think I stopped at a Wendy's one time. Otherwise I ate in the camper, pretty much what I'd have eaten at home. I started out with a supply of pre-prepared stuff like taco meat & spaghetti sauce frozen in individual meals, and stuff to go with it. I stopped at grocery stores 2-3 times to restock.
Other than fuel (12-13 mpg), my only extra costs were admission costs here & there, and the mileage of tires & vehicle. I did one minor vehicle repair, entirely DIY. It was a very good, memorable trip.
Jim, "Women over 50 don't have babies because they'd put them down and forget where they put them."