I've tried:

The Topeak RX rack. It cleared by thighs but was not stiff enough to keep a 10 pound pannier out of the spokes.

An Axiom rack. I had to cut-off the front to clear the seat, and the huge clamp did not clear my thighs. It worked fine with panniers though.

The Delta Post Porter (quick release). Did not clear my thighs. Worked fine with panniers.

Transit. Almost cleared my thighs but wasn't usable. I didn't bother to try hanging anything on it but it seemed steady.

A quick-release mount for the rack bottom or hiring a local frame builder to add eyelets is probably a better idea.