As far as the wakeboard demographic, just think about the local scene. Core riders, weekend warriors, everybody. With what you already know you could piece something together with some thought. Without doing any research - here's a very very basic demographic of my area (SE Nebraska):
core market: Males age 12-26, Ave household income between 60 and 90K. They live in cities/towns either over 10K people (which there aren't that many in NE) or in a bedroom town within a 20 minute drive.
That's really basic, but you get the idea. Think about what kind of people you see riding, at all, regardless of skill level. What you see at the ramp, boats and tow vehicles, who, out of those ride, or just have a wakeboard....Think about what you're trying to market - the above is more for boards/bindings than boats - obviously. You already have a good idea of your demographic, because you're part of it. Think of where you stand and try and figure out where the rough boundaries are. you're not going to hit everybody that rides, like the 60 yr old men, or the 10 yr old girls, but you're in the core group, so you should already have a good idea of what you're looking at.