Good Morning,
I have attended the Adventure Palooza in Missouri twice. It has been a lot of fun both times. It's a sort of scavenger hunt across the State of Missouri. It's a two-day event and although you may be riding with a small group, you're participating in a much larger event. That's evident when you get to Mexico, Missouri at the end of the ride.
Here is the link for their website:
http://www.adventureridersllc.com/