Make Beginner Board

I have an O'Brien Alias 5' that I would like to modify so that it is better for beginners. I am purchasing a new board (probably Phase 5 DD) and would rather not purchase another beginner board. My wife is a beginner, and I regularly teach others to wakesurf. Just this past summer alone, I think I had 10 new wakesurfers hooked on the sport! The biggest complaint I had about the Alias was that it was too "slippery". It doesn't hold the line that well. I really like this, but I can understand why beginners wouldn't. I was thinking of just adding a fin to each side about a third of the way from the rear. Does this seem like a good idea? Will it stabilize the board significantly? Any suggestions on fins? Any advice on drilling the holes to mount them? I don't have a router, so I was hoping to just get fins that surface mount. I will pull up the top padding, mark the drill locations (use cardboard to create a template from the fins), drill from the bottom, attach the fins, and then stick the padding back down.