There are two places in PWFP for RV camping. One is the concessionaire run, PWFP Campground (formerly known as the travel trailer village). The other is Oak Ridge Campground. PWFP campground has full hookups and a pool. It is located off Va Rte 234 just northwest of I-95. Thats where there is rush hour driven traffic morning and evening. Oak Ridge is tent and primitive (no hookups) RV camping. OR is off Va Rte 619 and is a two lane road in a rural setting. OR is not a busy campground. There is a camphost site at OR with at least electricity. I cant help you regarding what the cabin camp host sites are like as I've never seen them. The main thing to be aware of is the ongoing I-95 construction this summer. It is best to avoid I-95 it if possible. You could come up rte 50 to the beltway, around to I-66W, then out to Rte 234 South, which you'll take to the south. Its a longer route, but could take less time, depending on when you come. U can check for closures here http://www.95expresslanes.com/. You did not say which cabin camp you are hosting. This morning I drove through cabin camp 5 (the cc 2 and 5 entrance is Mawavi road off of Rte 619). Now I understand that the cc host accomodations is a cabin, not an RV site. It looks to be about 700 sq ft or so with a covered porch. There was electricity there. I would have spoken with the host(s) but no one was around and no guests were in the camp either. There are cabin camp area photos on the park web space. Look here for the links to photos and maps: http://www.nps.gov/prwi/planyourvisit/cabin-camping.htm
Photo of I-95 express lane construction.