Wow!

I don't think I would send Hobie Waves on a 15 mile distance race... You might not see them again. You might set up a race with resonable length legs and run laps. Each time a boat passes through your gate/committe boat it can be scored as a lap. The nacra could do 10 laps for the 5 laps that the wave might do. The advantages are that you keep the boats closer to the beach where in case of a breakdown they don't have a bad experience. You also have to pass the other boats in a lap race which gives everyone the feeling that they are indeed racing each other and not just the clock. Sailwave will allow you to score each lap by taking the time and then compute the overall winner no matter how many laps they do or don't do. The racers will see if they are getting better on each lap. Everyone will hit the beach in a reasonable time spread and be able to start the social part of the regatta.

I think the last thing you want is to have the poor wave sailor finishing 1.5 hours after the Nacra.

Just a thought
Have fun no matter what!
Take Care
Mark