Rubicon is an awesome venue but the trail definately gets backed up. I don't think Barrett is an option as it is WAAAAAAY too small to have that many rigs on it. Besides there isn't much room around the lake. I doubt Dusy is an option as there isn't a centralized meeting place.
I wouldn't mind seeing something local (Fresno area). Although attaining a permit for a large event in the area is near impossible, you could still do a gathering but it takes some planning as the stipulations the FS has in place are tight. Anyway, you could setup @ the Moon-light base camp (plenty of tow rig parking and camping) and just have scheduled runs out of that area. Bald, Coyote, Mirror, Swamp, Brewer, and even the top end (the fun end) of Dusy could be run in a day no problem. Then have the dinner @ base camp. Plenty of wheeling and tow rigs @ your campsite.