I had my '03 Fleetwood Elkhorn in a 2007 Chevy, new body style truck. It did fit but it was close. The little bump out at the back on the driver's side for the plumbing caused problems. I couldn't load the camper centered on the truck. I had to load it all the way against the passenger side wheel well. This left enough room on the driver's side for the bump out to fit inside the tailgate opening. It only ended up being off center by 2 inches or so.
What was aggravating was that the camper was already heavier on the passenger side. The off center loading increased the weight bias that direction even more. Good thing I had air bags that I could run different pressure in. I think it was about a 20 psi difference to level the rig.
Clearance on the bed rails was no problem. Clearance above the truck cab was no problem.