Yep, We never reserve a campsite at Mount Pisgah. Most of the Federal campgrounds on the NC BRP have about 1/2 of the sites as walk-up sites that cannot be reserved. These campgrounds can fill up during Holidays. When it's +90s and humid in the lower elevations of NC, Mt. Pisgah at 5,000 above sea level has very nice temps in August, see highs of 70s to 80F. No water/electricity at the sites, but not really needed with Ollie. I have been using a portable dump tank at Mt. Pisgah, but thinking about taking an extra length of black/grey dump hose keeping Ollie closer to level because of the descending grade at both ends of the dump station.
Don't know if Balsam campground has walk up sites or a dump station, it's above 5,000', it's a Federal campground not too far from the NC BRP. The highest campground in NC, around 6,500', is Mt. Mitchell SP, but it's tent camping only.