I got something done today on this never ending project. I bought some C channel steel (1″x2″, 3/16″ thick) to replace the stock bumper mounts. I cut them long enough so a third bolt can be used to secure, just like the stock VW trailer hitch set up, and just like the RMW bumper system. With those channels rough cut and inserted I was able to offer up the bumper to the van, fitting it to pretty well its final position.
I attached the unfinished swing away tire carrier.
And popped on a spare. I was worried that I had screwed up my measurements and the tire would cover part of the left rear light. But It clears it ok.
The bumper was not attached to the rails so it did tilt back a little. The tire carrier upright should be closer to the hatch.
And swung out, the tire clears the van.