I think the sensible way to do it would be:
Each rider is responsible for their own bike, clothing, safety, spares, insurance, etc.
We dont mind sorting the venues, route, Ill provide the jeep for storing all the spares etc. But theres no way we/I can provide spares/parts for everyones bike. And I dont mind sorting a website for sponsors.
Dont worry - It will all be worth it when you get to ride these: