There is a KOA just east of Washinton PA about a mile off of 79N, exit 33. It's a typical pack em in KOA but has pull thru sites. 33 is the last exit before 79 ties into 70W for a few miles before splitting back off north at Washington. That's about your only option. Most of the private campgrounds in SW PA, of which there are only a few, or around Morgantown WV, will be packed with the migratory Marcellus gas field and pipeline workers that time of year. There is also a KOA at exit 67 in WV, about 80 miles south of Morgantown. 67 is the first exit you'll come to on 79 after getting on from 19N. Watch the cops in Summersville WV on 19. Do the speed limit.
About an hour north of Pittsburgh you could try the KOA at Grove City, exit 113 or Bear Run at exit 96.
