I agree the prop probably will not help.
It took time to learn my boat and how people and weight affect the wake - 2007 SSV 22'.
Mostly, I go with 4 adults - 1 driver, 2 on the surf side back seat, 1 surfing. But when I get more people, I have to adjust. I have 750#s.
Not doubting your ability, but I watched people all summer start to get slack in the rope, drop the rope, ride a little, then fall out of the pocket. The boat would stop, I would get them back up, then the whole thing would happen again.
I try to tell people (before they drop the rope) to learn how to go from the back-pocket of the wake to the swim platform. Keep on doing that (back/forth) until you get the feeling, lean, and edge of the board. There is a skill to learn on how to try to get back into to pocket when you start falling back. A 5'6" board should be fine. I'm over 200# and most of the newer and smaller people fly on that board.
Mark