Pete Cz--There are a number of places in the Park where this would be both viable and make sense. Examples which come immediately to mind, mainly because I camped in them long ago (I guess it was more or less legal, since my companion in each case was the son of a Park ranger, and he not only knew what we were doing but took us the trailhead from which we started:
(1) Straight Fork Creek upstream of the "Million-Dollar Bridge." There's no trail in the drainage above that point, except at the utmost headwaters
(2) The Left Fork of Deep Creek--Again, no trails serves this drainage, although the Fork Ridge Trail does run the main ridge between Right and Left Fork.
(3) The Three Forks area of Raven Fork. No trail serves the Park portion of Raven Fork at all except one that crosses it at the confluence of Enloe Creek.
There are lots of other examples--upper Bone Valley (Defeat and Desolation creeks area and similar situations in many of the smaller feeder streams on the Tennessee side. Not for the faint of heart and particularly not for the inexperienced.