>>662159Double up! See the above!
>>665762Also, as to the general disussion: A "three-season" bag can easily be fortified for colder seasons (except "expeditions", e.g. Antartica and the Himalayas).
1. get a nice bivy, waterproof bottom, DWR/breathable top.
2. Wear ALL your clothes to bed. Yes, don't be an idiot. ALL your clothes.
3. Get a thin silk liner
4. Bring an extra $5 fleece blanket, sow it into a bag for your waist/legs.
5. Wear MORE clothes.
Illustration by Mike Clelland! (Get his books)