I am renting Dyracuse riding park in Wisconsin for the day. The cost will be $25 per person or less if more than 9 show up. Here is the link to their site. http://rapidangels.com/
The place is super cool. A long sand track like Southwick and Hard Pack clay track like most of the Midwest. And trails with rocks and mud and hill climbs. Very technical and long straight aways that you can reach upwards of 60mph.
Bikes and quads are both welcome. Only rule is you must go the correct dirrection on trails. otherwise you may be kicked out. Way to dangerous to not follow that rule.