It's a bit extreme, but did you try Antarctica expedition suits? They're designed for minus 30c or below. Or just the top and one or two hiking overpants. Also

It's a bit extreme, but did you try Antarctica expedition suits? They're designed for minus 30c or below. Or just the top and one or two hiking overpants. Also mittens if you need your fingertips. Got myself some of that but it's not cold enough to try yet.