I've used this mount:
http://gopro.com/camera-mounts/roll-bar-mount/
On a Mastercraft tower the rope loops around a nylon (I think) sleve with rotates.
I clamp this on here and it follows the handle perfectly.
As stated before the GoPro is not ideal for recording from the boat. I use it to record my girlfriend wakeboarding, she learning and its clear enough that she can see her body position.