Bill,
I second the Foxfire Campground. If you are looking for something closer (it is at least 30 minutes), and aren't staying more than a couple days and are just looking for a place to park you might try this
http://www.stalbanswv.com/parks.shtml St.Albans is about 15 minutes away.(I grew up there)This is a "roadside" park, between the river and a 4 lane.
I don't know what kind of place you are looking for, but if you want something "interesting" there is Big Earl's Campground adjacent to the Hatfield & McCoys ATV trail. or this one
http://www.littlecoalrivercampground.com/campground.htm Both are maybe 25-30 minutes from Charleston.
Kanawha State Forest is nearby, but I don't believe your rig would fit in there.
OH..I almost forgot. This place is on a beautiful stretch of the New River
http://www.newrivercampground.com/index.html Not too bad of a drive. Lots of areas to explore around there.
Hope this helps