hikerfast said:
i saw some thick down pants on ebay but they are gone, the whole search only showed up one pair.
My Opinion: You better stay away from down. Especially if your intended use is an unexpected bivy. If you have to stay out overnight or if you get hurt and need warmth, the last thing you want to worry about under those conditions is having to keep your down clothing dry.
I would be looking to put something syntheic and very warm on over my base layer and then cover that with a wind proof garment i.e. a lightweight rain jacket/pants combo, 3m propore, gore-tex a nice windproof / water proof shell.
It's got to be enough to get you through a night. Not to mention you better have some shelter i.e. a bivy sack. Something quick and easy to set up.
Whatever you carry, think of the total system as multi-function, multi use garments/elements that in the end will give you warmth and shelter and at the same time keeping the weight reasonable.
If I am going out solo for example in additon to layering my garments intelligently, I'll pack an OR waterproof bivy shelter.
Actually, I usually pack as if I am going out for the night regardless, full pack. Food for an overnight and breakfast.
If you don't bring extra or enough food, you can sit in a zero degree bag plus clothes with a 4 season tent and still freeze you butt off because you have no fuel, stoking your engine.
If I am going with a group, I usually bring less, but I always bring a layered system for clothes to make sure I am warm and dry if I get in trouble.