The numerous times I have been there, during the first two weeks of September, A jacket was only needed for around the campfire. In the morning and evening I am walking and generating my own heat, while wearing some lighter clothes and long johns. I carry a lighter wool vest along for the first and last hour.
I agree.. find some old wool sweater or two. You will end up taking it off after 7:30am or so anyway. I also wouldn't worry so much about camouflage as good earth tone plaids or solids.
ChuckC