Big rims would be nice, but I have these. If this does not work, I'll always wish it had.
On with the show, that doesn't really have much of a show...
The finished product. Nothing complicated, rim, 3/8" plate, 2X2-1/4" tube, Vice that has been mounted to another 3/8" plate and a receiver adapter tube welded to the bottom.
The real complication was adding 3" of 2x2 to what other 2x2 tube that was not quite long enough. After welding that, I used the oldest trick in a welder pocket, grinder and paint!

My goal was to have the vise base even with the weld table. I missed by 3/8". OK, so which idiot forgot about the 3/8" plate at the top? Good help is hard to find. I blame the guy in the last pic. He was too busy doing something or other.
I still have to drill the cross bolt hole. That can wait a few days, i doubt the vise will jump up 3 inches to escape.