With the idea of the water ski system, if the centre of spin was the board, i'm sure it would work perfectly, as your weight will pull you off, however if the centre of spin was your hips for instance, the only mass producing g-force is that of the board, which will be MUCH less. Another problem is that the drag this board will create will be quite high, so to stop it just coming off in the wind you will have to set the force on the bindings pretty high, so then if the board needed to release in some direction where the wind was not also creating drag (sideways for instance) the amount of spin to create the correct amount of g-force for detachment would surely be well above that which would kill you anyway. Did that make any sense?
I'm not saying that i don't think it will work at all, but you need to think really carefully about how the experience in the air is different from that on the ground.