I've been looking all over the place for a solution to this too.

I've a 3 season bag, comfort down to 4c, but it's just not enough to keep toasty at the begining and end of the season. I can improve on that by adding in the silk liner, which takes a couple of C's off

I was, and still am torn between a bivibag to put the bag into, or one of those bivibag come tent things, for reallllly rough camping.

Any offers of advice ?

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