Harper's Ferry is less than an hour from my house, and I have made many trips down there specifically for the joys of back road driving, mostly on my motorcycle. You do not have to go very far from Harper's Ferry proper to enjoy many, many miles of completely deserted country roads, some excellent twisties, and one road in particular where it is very easy...far TOO easy, to catch some air if you aren't careful. While Harper's Ferry itself is generally pretty crowded on weekends, they have a large parking lot and a shuttle bus system to take you into the park. I, at least, think it would be a great place for a meet. If you would like me to plot out a route for the road-rally portion of the meet, I would be happy to oblige
The Skyline Drive toward the end of October is going to be one giant RV convention, as it is "leaf-watching" season. The Shenandoah Valley would be nice, and uncrowded. We could meet at Luray Caverns or someplace like that... or Battlefield Crystal Caverns right off 81 in Strasburg. A good friend of mine knows the owner and could probably set something up for us.
One other suggestion would be Antietam Battlefield. The drive through the park is beautiful, if slow, and there are, again, lots of good roads right next door.
I would happily volunteer to do some of the ground work on this, if we pick a location within day trip distance for me.