I'd also be too nervous to go that light.
My favourite survival bits are:
Fluffy merino sleeveless vest, close fitting. Buy far too small then cut under each armpit to make it fit. I often carried two as they give so much warmth for the weight.
Long johns - city undie type made for warmth and lightness, not the tough and heavy tramper's ones. They might only be made for girls, I got mine secondhand.
And for those unexpected evening sleepovers:
Goose down jacket, if you can keep it dry. So much yummy warmth in such a tiny package.
Goretex bivvy bag, a glorified sleeping bag cover with mosquito protection. Keeps you untormented, dry and out of the wind.
