SSSHHHHH! Mike, don't tell anyone! It is a terrible place, roads are horrendous, you will destroy your RV trying to get into the area, all kinds of scary people hanging around.
Repeat after me, "There is no boondocking east of the Mississippi".
Just kidding, great place, kind of remote for some people. Expect graded gravel roads. The camping area is reclaimed coal mine land. There is also active coal mining nearby and those areas are off limits.
Hiking, biking, fishing. Most if not all of the camping areas have pit toilets. If you stay there be sure to visit
The Wilds.
There is also free camping in the Wayne National Forest in Ohio. But don't tell anyone that either!