The ... uh, ultimate shoe re-location test would probably be regarded as a demonstration of insanity rather than free will. Your experiment would seem to fail, just as it approaches certainty. Free will, therefore, can never be demonstrated.
Unless you can induce a turtle to remove his shoe of his own free will, and place upon the head of the turtle immediately beneath him, and that turtle remove his shoe and place it upon the head of the turtle beneath HIM, and that turtle to.... and so on.