Nice trip log. Thanks for sharing it.
I'm an igloo camper and I thought I'd share a trick with you to keep your water bottles from freezing overnight. If you take your Nalgene bottle of WARM water and drop it into the snow (upside down) and bury it, the insulating property of the snow will keep your water from freezing except on the very coldest nights. Remember to drop it in upside down however, so that if it does partially freeze, you'll still be able to drink from it (water freezes from the top down).