I think we need to have a workshop day. Service in the order of signup, everyone turns out to help, we get as far along the list as the day allows, and each person pays, say $20 an hour to the club treasury for the time their car is being serviced. If the car isn't mobile, everyone comes there. You're the host for the day. Throw in some burgers and beer if you want.
Anyone can come watch but if they don't help, they don't get the special labor rates on their car.