[Yoda]

what about full length mirros? how can you correctly use these to help? I
know TGM is against "position" golf, but I would think that you
could still use the aid of a mirror to make sure you are doing what you think
you are doing.

The Golfing Machine is Alignment Golf. Positions are important
to all golfers, but what differentiates TGM from other systems is its
precision alignments. And you absolutely should use a mirror to
monitor those alignments.