First off Tim, I'm glad the hypothermia didn't take you out. Sounds like you were pretty close there.

Second, great advice. I tried to use one of those cheap, pocket sized space blankets for shelter years ago while hunting. I got caught in a serious cold rain/snow downpour and it was my only choice. It didn't work for the same reason as you. Way too lightweight, it blew all over the place. I figure wind comes with cold so I have upgraded my packs with a much heavier variety. As well as a GOOD poncho with eyelets to string up an improvised shelter.

I've never needed to test this, but I was taught to eat as much food as you can when you need to take emergency shelter in that sort of situation. Force it down if you're not hungry because the digestion will increase your body temp. Also, and this one came contrary to my instincts, if you don't have dry clothes to change into, don't take off your wet ones. If you takeoff your wet clothes, they will just get colder and any progress you made warming up will be lost when you put your cold wet clothes back on. Keep your wet clothes on when you shelter and let your body warm them up too. Might be the only chance you have to get them dry. Make sense to me, but I hope I never have to try that one out.

Also, another plus one for liquid IV. That stuff is legit. I like the 'energy' variety that has matcha green tea in it. Matcha has decent caffeine content and releases slower, so no shakes (if that's an issue). Kept me going during a two day, hot shooting class in July. I don't like the taste of the energy one, but like all the others. Have a headache? Liquid IV works great for that too. Costco has them on sale about every other month or so.