I'm in a similar situation as you, although I plan on leaving a month earlier. My plan is to bring two base layers for the beginning, plus a short sleeve. I'm thinking something like cap 2 or a lighter merino or blend in a long sleeved 1/4 zip for hiking in etc. and then a merino hoody like above (maybe even something thicker like the Ibex Indie) that I can keep for sleeping or double up on layers if it's cold. Once temps warm up, likely after the Smokies, I'd probably send one of them home and just rely on my puffy for break/around camp warmth.
Has anyone had experience with any of the wool/syth. base layers? I've been looking at the Pata Merino 2, and that seems to be the best of both worlds. More stink-free than synthetic, faster drying than full merino, and overall pretty versatile. I'll have to check out that offering from Rab too.