My daughters and I wore 250 weight half zip tops and bottoms throughout the late muzzleloader season here in Iowa. We sat on the ground multiple times in negative wind chills for hours. This stuff flat works for the cold as a base layer in my experience.
That being said, the longest walk we had going in was about a mile, and we learned a long time ago to always start out cold; packing multiple outer layers (parkas, bibs, etc...) in backpacks until we get to the destination. If you're comfortable when you get out of the truck, you will be a hot, sweaty, mess by the time you get up the hill. We also stop often to avoid heavy exertion and to deliberately mitigate sweating.
If you can't mitigate sweating on the way up and into an area, I'm not sure there is a base layer that will prevent you from getting cold once you arrive. The guides in our camp in NW MT were old school and had 2 things to say about clothes and layering-
1- leave your cotton at home
2- bring multiple pairs of wool socks, wool long underwear, and a sturdy wool coat and pants if you can afford it.
The one day that we had snow and rain all day, every guide in camp had on their "woolies". Pendleton, Big Bill, or similar, pants with gators and insulated wool flannels on top with oiled dusters. We rode horses through the worst of the cover and hiked the last mile or so every day.