I camped out (in a metal trailer) on the North Slope and Beaufort Sea (300 miles north of the Arctic Circle) for 6 months one winter some time ago. 40-60 below pretty much every day. The only warm boots that worked were the air-bladder Army surplus rubber type, we used to call them "bunny boots" because they were white and made your feet look huge. But they would keep your feet warm enough no matter what the temperature. Any Army surplus store in Anchorage has them (or used to).
Hands are a different story. Your fingers are natural little radiators, so you need mittens not gloves for warmth. I needed to use my hands so I tried multiple layers of silk and wool liners under sheepskin gloves, but I still froze the outside fingers on both hands at various times. If I were going back, I would use heavily-insulated mittens for the outer layer and adapt as much equipment as possible to mittens (larger straps for ski/trek poles, etc.).
'80 FJ40, '86 FJ60, '07 FJC
ďThe Constitution is not an instrument for the government to restrain the people, it is an instrument for the people to restrain the government - lest it come to dominate our lives and interest." -- Patrick Henry