> dry snow, wet snow, sleet, freezing rain, or rain ...
I am not sure there is a 'good solution' for the middle three.
The problem is that when you are moving fairly fast you generate a fair bit of heat. You might need little more than a thermal layer under a windshirt. But when you stop, especially when you are wet, ... oh dear.
OK, a good windproof outer layer IS essential most anytime. It does not have to be waterproof or even WP/B, but it must block the wind from wind-chilling you.
In practice, with a whole lot of experience, some of us travel really lightly dressed even in stinky weather, and rely on training and experience to make the transition from fast movement into static shelter. But care is needed, plus a partner, for this to be safe. There have been times when we have been so wet and cold by the time the tent is up that my wife Sue has not been able to get her wet clothing off by herself. I have had to help her, and sometimes she has had to help me too.
Where the experince bit comes in is in two places: knowing just how far you can push it before you are in serious trouble, and having the confidence that you *will* warm up once you are changed. Getting that experience *safely* is not a fast process, so take care!
There are no really good solutions.