What you are displaying is not new to many of us. I can walk you to place like that in my own back yard. Weather like what you describe is also nothing new.
I do like your basic point, that your clothing is your survival gear. There are lots of high quality items out there that can do double duty. I'll just add that a few simple items, like a light piece of 5/16th's ensolite foam and some tear open chemical hand warnmers would make a big difference. You are only talking about 4-6 ozs. here.
BTW, if you get injuried, you may not be able to make a fire. Then a bivy sack, a tarp, or even a light poncho to roll up in can make a big difference as well. Ditto with having an ACE bandage along. Just the thing to split a broken leg. Again, just a couple of ozs. E