Get a combo seat like Flying Objects Transit, best of both worlds.
Adjustable height on the spreader bar with a mid strap.
You can have the hook low for slalom or high for waves. 
O - I know the answer to this one - I figured it out today when I saw my reflection in a car window.
Seat Harness - gut hangs over the top of the hook.
Waiste Harnes - gut hungs out under the hook.
The rest is choice!
