Hmm I never have -20 temps, but my cold weather system starts with a sweat wicking duofold base layer, then a fleece turtleneck, then a Gore windstopper windbreaker with a fleece outer shell, then a Browning Hydro fleece long jacket with gore tex.
I use a thin pair of wool gloves with a handwarmer pouch, throw in a heat pack if needed.
Also a neck gaiter, generic wal mart brand, and a pair of wind/water proof Bass pro bibs.
Oh and oversized Lacrosse burlies with 1200g of thinsulate, I use toe warmers when needed.
I've started using the disposable heat patches when it gets really cold, these
here work nice, I've also used the Ace brand.
The walk in is what can kill a mans hunt, you overheat/sweat, you get cold, so I pack all my outer layers in.
EDIT> Also have a Gore windstopper fleece vest that I use some times.