the most extreme clipless compatible boots are 45Nrth Wolvhammers. From my experience I think you'd never get cold in the PNW with them. Im in MN and I'm a cold feet all the time guy, and they're warm for about 2-3 hours in pretty extreme cold with a single pair of thick wool socks. They are totally waterproof, will accept any mountain style cleat, very well built, and also they are stupid expensive.

Yes, They might be overkill for you and there are probably a few others to recommend, but I have these and I can attest to their warmth and performance.