I read the guide for Shenandoah. Ok I can camp in designated zone. Does the within 50 yards of another party still apply or within 100 yards of hut etc? Can you camp anywhere along the trail as long as you stick to the regulations about 50 yards from trail and "no camp signs"etc? Try to figure out if one can just mosey along and camp when one feels like it or do you have to bust a gut and get to the 'designated spots".
The back side of PATC maps has the 2000 back country camping regulations printed. They include:
No camping within 10 yards of a stream or natural water source
No camping within 50 yards of building ruins
No camping within 50 yards of another camping party or no camping post or sign.
No camping witih 1/4 mile of a paved road, park boundry, or part facility such as a campground, picnic area, visitor center, lodge, wayside, or restaurant
No camping within 100 yards of a hut, cabin, or day-use shelter.
No camping on certain blue blazed side trails, Hawksbill Mountain, Big Meadows, or Rapadan Camp.
Updated information should be at www.nps.gov/shen.
I know that it may sound like there are a lot of places where camping isn't allowed, but there are still ample places to stealth camp. Not to worry.
The biggest "problem" is the 1/4 mile of a paved road - camping along the AT all too often is within that limit since the AT and Skyline Drive are often within 1/4 mile of each other. On the other hand one can often get away with stealth camping if one takes care not to be visible from the trail and from the road.
Another good source of regulations is : http://www.patc.net/hiking/destinations/snpbackcountryregs.html
As far as I know that is the exact text that is used in the booklet handed out in SNP where you get the backcountry permit.