Hey Red, one thing I never considered is the fact the rear half of the coach going down the road bounces alot. Anything you attempt to hang off the back of the coach will just enhance the bounce affect with more weight. We had that factory 1.25 hitch on our big horn, and my wife followed me as we left the dealer. We had just out bikes (maybe 60 lbs) on the rear hitch. She stopped me because they were whipping up and down something terrrible. That factory hitch is so long between the frame rails, with no extra support.. it flexes like a rubber band. We only went like 30 miles and I removed the bikes and never put them on there again.
I know SOB trailers do come with 2" recievers on them, but they also usually have their frames built differently than the lippert frame set heartland uses.