Hey rusty, I too am a surfer with a rib
pretty green with envy with where you live though. I would love to go exploring for surf with my boat but it is all accessible beachies around here and easier to go by land
I take my boat into the surf pretty regularly though, not had the balls to take it into stuff much bigger than shoulder high yet but I find that is plenty for some good size jumps
As per your cavitation, i sometimes find mine will lose grip in a tight turn if the water is a bit frothy or I open it right up in a turn from a low speed. The same happens if i land quite stern heavy without much forward momentum but loads of revs in an surfline jump.
I have always put this down to additional air around the prop either due to froth or the prop taking air back in when it lands, as it doesn't happen outside the surfline and I think I have got my boat pretty well setup.
I find if I back off the throttle and then power on again full grip is restored
Tidying up your prop will help though.
Any pictures? Would love to the boating/surf over there...