My cousin and I took a day trip out to Milford Lake on Saturday. It's a little over 2 hours west of my place in Olathe off I-70. Here's some footage. It's a good place with about 300 acres to ride for bikes and quads both. It's really scenic too, right along the biggest lake in KS. No camping at the OHV park, but there is very close by. The riding area is officially called School Creek.
Mokan Riders Offroad Club