Suther (Eric),
Hmmm... gotta ponder this one.
A screw is too slow, and I want to stand on one foot, while releasing the pinch with the other and holding the work with both hands.
That said: the idea of a wedge is intriguing - it could even be progressive - have a low angle at one of its travel for high clamping force, and a steeper angle at the other for a quicker release.
Ponder, ponder!
Thanks!