How about setting up something like a decathlon for kids and have the multihulls be one or two of the legs. My thought is that sailing would be one of the legs and swimming up to and crawling over a couple of cats could be another part of the course. Some of the other events in the race: Sprint, targets with slingshots, Hopping in a sack race, rings, ect. Idea is to make the catamarans stand out from all the other events but not make them the only focus. This way you may be able to see more kids than just those that know about boats.