I can run with my tailgate down and quad loaded if I put my Reese WD hitch in the 1,000# hole which extends it out an extra inch. Piece of mind will be an electric jack to avoid worrying about any potential contact with the current manual crank.
I have seen the carriers that allow 2 to ride above the rails for $1,000 but that adds 300# so in a half ton you might be right at your payload limits. I am looking at one when I get a second quad and yes they seem steep to load so a winch is in my plans just for safety.