Hi
Thanks for reminding me about the UV ,at my age things that I knew don't always stick.
It's not an adapter that I used several companys make swing away racks. I had a rack and thought about an adapter but thought one tjhat was desinged to swing would be stronger / better. This is the one I chose
https://rockymounts.com/backstage/
It swing complety passed the doors on my RT210 pop.
I forget the LBS rating but 500 lbs sounds heavy. I think we are at or around the weight limit. Although we do pick up some support from resting the PVC pipes on the bumper.
Good luck with your hunt
Michael