I started a charity ride 11 years ago. I canceled one year due to a bridge being shut down. I went to the local Lions club and they sponsored it, and now I am a Lion. They might be interested in sponsoring the ride for you.

I would do a metric and a 32 mile ride.

Contact your local convention and visitors bureau. They might be willing to help.

Stay small to start with. Volunteers are the hardest to come up with.

Good luck.