Labor day in the Shenandoah, I would not take too many extra clothes. I wouldn't take more than one short sleeve wool/poly shirt, a rain jacket (Driducks will be fine there)and your UL hooded sweater on top; maybe a windshirt too if you have it. Extra shirts and more than one extra pair of socks is really not necessary. You'll be under the trees so don't worry about sun sleeves. Your UL sweater has a hood, so I wouldn't bring a wool hat.
On bottom, I would take, at most, undies, shorts, long john bottoms, one extra pair socks(wool or poly, but I prefer wool usually), and a rainskirt or dri ducks bottoms. I really can't imagine wanting more than that. I wouldn't even bring the convertable pants.
You can make a fine rainskirt from a trash bag. You may never need it but its a cheap and easy addition.
As to to night time temperature, its likely to be a bit cooler in the elevations than in the towns. I don't think I would need more than a good 40 degree bag.
There is a lodge on the AT there if you want to re-supply or get a nice meal while walking.