Glenn
I had a 30 degree bag and spent a night at -40 in it wearing a snowmobile suit and a light synthetic jacket and NO PAD! Fortunately I was buried by the blizzard, this was at the base of the Eiger in December. Oh sure I thought I was gonna die, but I did finally sleep, and wasn't too cold nor hypothermia when I awoke at sunrise. At least I think I awoke, if I died then I've had a really long bad dream.

PS I do not recommend this.
Jim