Holy cow - is that whole lift thing slotted into a standard 2" receiver hitch?? I didn't know that any hitch like that could take such a 'tongue weight'. I thought they were down in the 400 ~ 500 lb. range. By the time you lever a 600-lb bike out on the end, you'd be looking at some serious load.
I think I'd just go with a nice little trailer...
Or else a custom-welded non-removable platform that ties directly into the motorhome's chassis rails in back. That's a lotta load to carry...
Kirk