pretty good suggestions
My cold weather “unhappy bag” is similar to what has been suggested here. The one thing I would add is at least two sets of long underwear. They are great a keeping you warm under the other layers and don’t take up much space or weight. I prefer Capeline but other synthetics also work well.
By the way, we call it an “unhappy bag” because the only time you go into it is when you’re not happy - you are cold, wet, etc. It’s also called an “unhappy bag” because once when I needed stuff from the “unhappy bag” I found that I had left it home. I was very unhappy and very wet and cold. Good thing my friends had their “unhappy bags” (that’s why I pack two sets of long underwear).