Old thread got resurrected. From the look of your pictures it is pretty obvious the boat is a V-Drive. I am guessing the OP's boat is a Direct Drive launch?
That would seem more in line with having one 70 inch long back locker?

I measured my 2001 Launch SSV back lockers and got just above 20 (21-22) x 19 x 46 long.
I got the 750 lbs fly highs in back and they are 20 x 20 x ?. Anyhow the locker is 20 or more in one dimension meaning the sac can fill to the limits in that direction.

To the OP I would assume adding the fat sacs in the locker and under the playpen is a good start for getting a wakeboarding wake out of the boat.
Play around with that weight and add a sac on the surf-side of the Direct Drive. Probably something like the Ronix 1100 lb?

A surf-gate seems like a good idea.

Mike