I noticed that this is your first post, so
I've been towing 5th wheels for a long time (I started when we lived in Mount Vernon, Ohio) and have never seen a facility that rented out pickups that were equipped with the 5th wheel hitch and trailer brake controller needed to tow a 5th wheel. Perhaps there may be some, but I've never run into them. Good luck in your search! I guess you could check with truck rental places as well as RV dealers in your area to see if any of them could point you to a source.