At a resent GP I noted several people roling a large bag into a sausage.
Then using this to surport the full lenthe of the lower leg the result of this
ment next to no weight was on the foot and the knee was 4-6 inches of
the floor most people didn't see this as a infringment.
But the rule does say 3 points of contact with the bag used only to keep
the knee clean not elevated.