A build-off ski should be a ski designed and built for the build-off. A ski with something extraordinary that sets it apart from the skis on the rest of the beach. There are some killer skis on the beach that deserve attention, but then it would be just like a car show, not a build off.
Build-off skis should be noticably custom. Remember watching the biker buildoffs? They werent just bikes with some aftermarket parts and a good paint job. They had definite point, whether super clean old school, no wires, hoses, ect showing. Or crazy custom wicked twisting frames. The builders had a specific design and the purpose of the design and build was for the build-off.
IMO, the buildoff should be something that not everyone can enter. Skis being build over a couple years would not qualify, unless you did a MAJOR overhaul on it for the buildoff. As for classes, I guess pro and amuetur classes would be ok, but limit it to like 3 boats per class, or have them all together and limit it to 4-6 boats. A lot of skis kind of dilutes the custom/inovative feel of the build-off. I thought 6 was a lot last year. Be picky on the build off, then have a couple none buildoff awards to give to people on the beach. That was cool last year.
If it would blend in with the skis down on the beach, my opinion is show it off in a build thread not the build-off.