Never did hear back via email, so gave Rhino Hitch a call. Guy stated that the shank is rated for 10,000 pounds of
tongue weight, not trailer weight. I confirmed that with him a couple of times and ended the first call there.
I went back to the Convert-A-Ball website and saw that they list their ratings for GVW, so I called Rhino back and he said that he was told by Convert-A-Ball back in the day that it was for tongue weight.
To say the least, that's not confidence inspiring. And while I can't say definitively that Rhino is wrong, I'm pretty darn confident they are. Unfortunately, that
fundamental misunderstanding is enough to call the entire hitch into question for me and rules it out as an option for a hitch for me.
Convert-A-Ball website (from earlier in the thread):
http://convert-a-ball.net/cab/the-original-convert-a-ball-interchangeable-ball-system/
To anyone else who wants to go with the hitch but replace the Convert-A-Ball I did confirm on the phone that it's a 1" diameter hole, so you could put any ball in there with a 1" shank.