Fishnet base layers. They work, and you want them.

[THLR]

Here's where fishnets are stellar. Temps drop towards -10°C in the morning, significantly warmer in the sun but well below freezing.

I'm wearing woolnet x2, a wicking layer and windbreaker. Note how I don't need my puffy for glassing as I'm basically dry

 

[isleofGough]

Still, down or synthetic down are needed if you are standing still in sub zero temps.

 

[fwafwow]

I'm wearing woolnet x2, a wicking layer and windbreaker. Note how I don't need my puffy for glassing as I'm basically dry

Sorry for perhaps a dumb question (one of my specialties), but do you mean you are wearing two layers of Woolnet?

 

[THLR]

Not at all. Yes! I wear a woolnet tshirt, a thin woolmesh crewneck (smaller holes) and on top a hoodie; this one made for winter trail running