Allstays is pretty comprehensive, listing Corps of Engineers sites. It also lists reviews for various campgrounds. Call those cgs listed to see if they have sites that can accommodate your rig.
My brother and his wife stayed at ACE Adventure Center Campground and enjoyed it. They have pull-throughs.
Here's the Allstays listing for Summersville.
SummersvilleHere's the zoomable state map so you can expand your search. I see several very close to the New River Gorge.
Map
"The only time you should fear cast iron is if your wife is fixin' to hit you with it."-Kent Rollins
First law of science: don't spit into the wind.
Magnus