Thanks, Warden! I had never heard of the closed foam. Found some and will give it a try in my next fridges outing.

take a look at UD Fastpack offerings- I have both the 15 and the 35, they also have a 25- one of those should work depending how much kit you need to carry

 

for a "sleeping bag" I would think you would want something along the lines of a survival bag- an Climashield Apex quilt would work well, light and packs small- less effected by moisture than down- I have one that has a poncho hole in it so I can throw it over the to of me like garment- that could be handy; a lightweight bivy would be worth carrying in the event of an emergency as well

 

in really cold weather (and longer duration) bladders simply won't work, regardless of how diligent one is- I use wide mouth Nalgenes (they come in 1/2 and 1 liter and even larger soft sided sizes)- I wrap them in closed cell foam and carry them up side down- this keeps the threads from freezing