Spec wise you don't have a problem with the carrier, Don. Looking at the hitch adaptor though, it looks as though it would move the carrier mounting point further away from the vehicle. This would put an increased cantilever load on the RV hitch which could exceed the 400lbs limit over bumps. My suggestion, if possible, would be to fit the carrier straight to the RV in the usual way and make up a slope/platform out of flooring grade chipboard that you could walk up when pushing the bike up the ramp. It would probably only need to give about a twelve inch lift and I would think could easily be stored somewhere in/on the average RV.
FWIW.
Ken.