A rail could work. I think a small board or sheet of hard plastic would be better. Depending on how it is designed, the whole shaft could ride on the plane angle. This would be good also for visualization of the plane also.
If the heel of the club only is touching the plane board, you can still see the ARC of the clubhead on the ground, as the clubhead go back, up, and in... down, out, and forward.
Threaded Mode
