We go there all of the time. A bunch of us have campers there. The land is private, but the owners let folks ride there. I was told there is about 3500 acres to ride. I've been going for five years and we're still finding new trails. Everything from mild to wild. Two of the camp grounds will charge an admission (Springer's forbidden zone and Oak Tree). But if you enter from Clark Ave./ Intermodal Pkwy(mapquest 2400 clark ave) there is no fee.
Rules? Just have to abide by a few of the Ten Commandments (you chose which ones) and NEVER EVER leave your vehicle, 99.9% chance it will get raped, pillaged and burnt.
If you more info just ask.
And if your in the area Labor Day weekend we'll be in the campground just before the tracks just look for a white XJ we'll show you around a bit.
Guy