Owl--As someone who has spent his life reading and ruminating on the literature of the Smokies, I'll offer several comments.
(1) Kephart's book does not in many sense accurately depict the mountain folk of the time his was writing. If you want to see the other side of the picture, and a telling critique of Our Southern Highlanders,
read a copy of Judge Felix Alley's book, Random Thoughts and Musings of a Mountaineer.
He offers a scathing critique of both Kephart and Margaret Morley. Michael Frome, in Strangers in High Places,
has a good chapter on Kephart which is quite nicely balanced. Incidentally, if you haven't read From, you owe yourself that treat.
I see that Tenn Swede has already identified Harry Middleton's On the Spine of Time.
I knew Harry quite well and he was a dear friend. I don't think there's any truth to the characters he depicts, and being from the area he is writing about I should know. Perhaps mroe to the point, my 100-year-old father, who has lived in Bryson City all but the first five years of his life, assures me none of Middleton's characters are real people. Still, it is a wonderfully written, totally charming book.
I wholeheartedly agree with you on Nick Lyons. He too is a good friend and did me the great honor of writing a Foreword to my book on fly fishing in the Park. He's a rare talent and for all his self-deprecation, he's a much better fisherman than he would lead readers to belive.
I'll mention one other book which I think truly first-rate, although it is out of print and devilishly difficult to find. This is Ken Wise's Hiking Trails of the Smokies.
It is more, much more, than just another trail guidebook. Filled with history and charming notes on places in the Park, it is wonderfully well researched. He is working on a completely update version.
Hope this helps a bit.