motorcycle hitch
Steve,
I custom built a rack on the back of my 30' 5th wheel for a 300 pound dirt bike. With the weight of the custom built rack (never weighed the metal) and the 300 pound bike, that added "WAY" too much weight to the rear of the triler. It whipped and swayed like a regular trailer would that was loaded with too much weight to the rear. The great thing about a 5th wheel is the way that it tows like it's not even there. You put a 500 lb rack and an 800 lb bike on the back of your 5th wheel, it might make it so hard to control that you will never use it. I would seriously consider a smaller trailer to pull behind the 5th wheel just for the Goldwing. It would make it much better handling.
Good Luck,
Been there, done that