The way around waivers is to meet up in a public parking lot before the ride starts. If you start from a specific spot (a church lot) then the law "assumes" it is the church that is sponsoring the ride and are thereby legally responsible since they are the originators.
That's the way it is here in NY at least.
Becky, a real lawyer (I just play one on TV) might be able to clarify this a bit.
