I am not a fan of the MXZ surf wake. I've only ridden one with surf gate and 400lbs pnp in the lockers. The wake board wake is one of the best in the malibu lineup, but the surf wake is the worst. After my exp I did some thinking and I think if you get 750+, on top of the stock tank, in the rear surf side locker, at least 700lbs of ballast in the bow + the stock bow tank, and 500lbs on the surf side seat you should be able to get a decent wave out of it.
This is all speculation based on what we've done with other models, since I've yet to try it. I can get killer surf wave out of a VTX with the right weight, so I figure I could at least get a decent surf wave out of an MXZ if I had time to play with weight in one.