I go through this on a frequent basis. WMNF has very confusing backcountry guidelines and regulations. They either deliberately or unintentionally confuse the two. Leave no Trace is a guideline, but its not a regulation. With LNT you may be educated for not following a guideline while violating a regulation gets you a ticket.
So in this location on top of the cliffs the regulation is that you can camp anywhere you want even if that is in the middle of the trail. The boundary for the state park is some distance to the west off the actual trail and the Dry River Wilderness boundary is to the east by about 50 feet so special requirements for either area do not apply. There is no structure or campground within a 1/4 of a mile and its not technically above treeline so there are no regulations that requires any distance from the trail. On the south end of the cliff, the ridge is somewhat wider and the woods a bit more open. The actual blazed trail runs over the open ledges to get the views but there are open areas to the east on occasions (away from the cliffs). As the hiker goes north to the Mt Webster high point the ridge gets steeper and the woods much thicker. Google Earth has some pretty good resolution imagery and these open patches are pretty obvious by zooming in. The biggest risk is that some of open areas off the trail may have been used for a toilet so watch your step.
I generally advocate that if you stealth it should be immediately before dark and be gone soon after sunrise. head in the woods between Pierce and Eisenhower before it heads above treeline in the evening during thru hiker season and its usually packed with thruhikers, they come late and leave early, these are legal spots. Anything north of there along the AT to the woods as you descend down the Osgood trail are not legal and the terrain and tree growth on the Osgood trail make it impractical for quite a distance. Sphynx Col another popular "stealth spot" along the ridge is not a legal spot as it is above treeline and on rare occasions tickets are written.