I have riden a 750 sx with a Jet Dynamics ride plate and hull extensions and it was absolutely the best handling 750 I've ever been on. Those were the only hull modifications as far as I know. Haven't tried a ProWaterCraft.
Update the turnplate and pole pad to shorter SXI parts and find any extended rideplate. Jet Dynamics will work but may need to be shimmed down a little. Hull extensions will also help a lot but may be difficult to find.