Nice report Dave. You get any pics?
Next time your feet get cold, heat some water up and seal it in your water bottle. You can then put the water bottle in the bottom of your sleeping bag and it will help to keep your feet warm. Either that or some of those Hot Hands hand warmers.
I have done the freeze beer instantly trick
but I have never heard about water doing that. Same premise I guess. Pretty cool unless you are thirsty.