bike choice?

Ride whatever you like. However, keep in mind that this will be on gravel, grass and dirt. There will be very little pavement, as paved streets will be off limits, other than what you cross at intersections. Fat tires are good: mountain, cyclo-cross, hybrids, beach cruisers, recumbents (if you dare), tandems (only if your stoker is a stuffed monkey) and, if you enjoy being different to the point that your peers question your sanity and not your humor, you could ride a road bike.