Depending on the rest area, I probably wouldn't sleep well. I had a situation once where I was so tired I had to get a nap for a few hours, I think I was up all night the night before probably from a sick dog or something. That was useful. I hear some rest areas are better catered to RV's, that would probably be fine but I'd make my best effort to use a campground, harvest host, or love's stop. I prefer to be safe. I've never done the walmart thing, Harvest Hosts in parking lots of restaurants/wineries are about as sketch as I want to get.