The reason the started making adjustable stands.
You can sit on the top section, put your heals under the front lip of the bottom section and lift keeping pressure on the tree. Reach down carefully with your hand and try and adjust the cable/belt. One thing that always should be done is tieing the top and bottom section together that way if it falls you can pull it back up.
All of this requires no small amount of strength and balance. Your definetly on the right track though, practise is the key to safe hunting.