Bill, I think Hippie Dave lives somewhere on Deep Creek road. Might be able to leave a vehicle there (but you might have to donate a couple of 6-packs to him for payment!) I think the Steiners live closest to the dam parking area , but I don't know them.
When I was at the dam a while ago, two cars were vandalized in the parking area just to the right of the concrete overflow channel. I would NEVER leave my vehicle there.