I have a 38 foot cut away full keel with the same problem. And like you, the best I can do is short hard bursts in reverse then to neutral. It is a real crap shoot as to where I am heading in reverse. I try very hard never to have to back out of a tight space. On the good side that prop walk can be used when docking and I need to move the back of the boat over. it is kind of like a stern thruster.