I think that it would be a good idea and I would enter. Maybe the whole thing would be easier if you just had a few generalized classes similar to what is in real shows.
Reining or cutting
All around (for horses who don't fit any other events... like ranch or trail horses)
Novelty (includes all novelty pix. Funny, tails, cute foals, costumes, etc)
I also think that a bareback class would be awesome....maybe a bareback horsemanship that would work for both english and western riders.
No offense but I think a big turnoff are too many items to choose from. Simple and straightforward would work better, IMO.