I would not put a PR-1 or anything that heavy on a mount like that. You could probably build something with plumbing parts, section of pipe pipe cap drilled, a short bolt, couple of washers and a wing-nut.
@ Steve, I've tried the pipe & drape thing, doesn't work that well. You always have that "lean" or tilt to one side crap going on...I know tripods are a bit ugly, but nothing else really works that good.
Even tried pipe with a strong Iron patio umbrella base. Fail.