Holy cow I didn't think I would ever master this move! I've been trying it for months now. Yesterday I finally had this idea to flip my hand over and try the move with my hand in a different direction. When I did, the move went instantly from scary, uncertain and clumsy to incredibly easy. Just like that! It's amazing the difference one hand placement can make in a pole trick.
So now I present to you, the progression of my shoulder mount flip over move: