I have a TERRIBLE time keeping my feet warm (I mean really bad).
A couple years ago I bought a pair of Cabela's Inferno Pac boots and they are the best thing I've ever owned for cold weather. I bought them becuase I was going on a late muzzy hunt and the air temps were somewhere around -20. I wore a pair of silk liner socks, then a pair of heavy wool socks and my feet never even thought about getting cold, which is an absolute miracle.
They're big, but not so much so that you can't walk or climb a tree comfortably.
I just looked on their website & they're still available & even on sale.
Just make sure to get them at least a size bigger than you normally wear to allow for sock layers, and a little bit of room for circulation & air- that's really important.