I e-mailed my contact there. He might have better info than what you'll get from the reservations people.
We made a day trip up to the Conway area a few weeks ago, partially to scout out the charging scene. We were really close to the rated range being exactly what we needed to get back home at the end of the day, so I started hunting around for a camp site to charge up for an hour or two.
tl;dr:
Eastern Slope Camping -- Avoid at all costs
Pine Knoll Camping -- Wonderful and accommodating people
The first one was a place we had previously camped, Eastern Slope Camping Ground was a shocking experience. The very nice ladies at the front desk understood what we wanted, and one had even heard about Tesla before, and they called the owner of the site to get permission. This man flat out refused to let us charge. He said that their electrical hookups weren't built for charging and that it might damage the hookups. When I told the lady who was on the phone with him that we didn't need any special equipment, just the standard 14-50 hookup that all the RVs use, and that this was a very common thing that many campgrounds all around the country would do, the man began yelling at her loudly enough that I could hear him from the other side of the desk as he told her he wasn't about to change his mind and that was that. Obviously they won't be getting any of our business for future camping, either.
We drove down the road a way and on a whim I pulled into another RV campground, Pine Knoll. Again, the lady at the front desk called the owner to make arrangements, but this gentleman was very nice and told her to send us out to a lot that was near where he was currently located. We drove out there and he came to meet us. I showed him the UMC and hooked up. He was very impressed. I asked him about the price, and he asked how much electricity I was going to use. I told him that it would be maybe 30 kW which at the most would cost 4 or 5 dollars for a residential service and I also told him that I had heard from many other owners that a lot of campsites will just charge a flat $10 charge. He said that was fine with him.
It was drizzling out, so he walked us over to where they had a big campfire going and a bunch of people were watching a Bruins game. We stayed and chatted with a bunch of people for about an hour and a half before heading back out. When we got back to the car, the owner and a couple of other guys were standing nearby talking about it and we had a few more minutes of Tesla Time then made the drive back home. It was a great ending to a nice day and a very nice counterpoint to the earlier disappointment.