I've got about the same boat as well. I can surf just fine with stock ballast full in center and surf side with some extra human ballast. This boat likes extra weight in the rear. I borrowed a 750lb bag from a buddy and put that half way on the seat/swim deck on the surf side and got a great wave with only a couple other people in the boat.
The guy surfing is factory 400lb bags in rear, with front full and 3 others in boat on surf side (1 being driver). The girl was with the extra 750lb bag with about 5 people in the boat. Definitely get some weight in the rear, then adjust and throw human ballast around towards the front to figure out length. I usually have wakeplate around the same as kev... anywhere from 50-75% up. Not sure on speed since my speedo is broke, but usually im around 2800-3000 RPM on PP with a 14.25x14.5 OJ prop (A must upgrade if you dont have it).