I am not a boat racer and, in fact, have never been to a boat race..yet. (going to Key West!!)
My viewpoints come strictly from my experiences and views of racing on both the sportsman and professional level in NHRA drag racing.
One thing that needs to be mentioned is prize money. I doubt that there is any motorsport where prize money alone will pay the bills. In the Utlra competitive world of NHRA Pro Stock racing, we only received $4000 to qualify for an event, and maybe 20,000 to win!
If we would have won EVERY race that season, we could have made a small profit.
The point is that sponsors are the only ticket to making it work financially.
Again, I do not have experience with offshore racing, so these are just general observations, but my opinion is that there can be many classes of racing (NHRA has 8 sprotsman classes and probably over a hundred categories within those classes) but the format is what is important.
Draw up the rules so that the "professional" classes (supercat superV, etc.) can compete on the day that can potentially draw the biggest crowd. All other classes can run other days, with possibly finals in the category on the big race day.
It needs to be fan friendly as you stated!
In my experience, fans pay the sanctioning bodies bills (and salaries) but the corporate sponsors pay the racers.
Professionalism is very important, and will come to all the teams when sponsorship dollars are on the line.
If you don't want a carnival, thousands of drunken idiot fans, TV in your face, and big purses, then enjoy it as it is now!