Obviously too late for this post, but for the rest of folks...
I live and hunt in North Dakota, and I and my German Shorty hunt even when it's 10 below...Here is what I wear:
Under my bird jacket, I wear one good coat (I sprang for the Filson w/ the wool liner), one long sleeve shirt, and a t-shirt.
I just wear long johns under my brush pants, and here is the key...
Wear the thinnest wool socks you can (again, I use Filson light weights) and just my normal issue water resistant hunting boots. With all the walking, I don't want big thick socks where the air can not circulate, and make my feet feel stuffy. And just good huntin' boots.
I prefer thinner gloves so I can load/reload/work the safety, grab my whistle, etc. Yeah my fingers get cold for the first 20 minutes, but after that (or you gwt into the birds!) I don't notice it...the blood is going by then.
Oh, the other key...have a neck gator or balaclava to block the wind around your neck.
As for the face...well, it just gets cold. And use a plastic whistle if it's below freezing :shock: