I like the 1st boots Atec listed. full length gaiters on them would give you another 10 F of warmth. All the others are feltpacs. Warm but heavy.
My BEST recommendation for most bearable winter weather (to -20 F), price no object, are Rocky SnowStalkers W/ 1,200 gm Thinsulate insulation )in camo only)
B/C they have a removable PU closed-cell foam liner.
This is very important in winter camping. Gotta keep felt or foam liners in yer bag at night so's yer tootsies are not encased in ice blocks in the morning. Gotta keep felt liners dry (to stay warm) by always wearing a VBL sock.
"There are no comfortable backpacks. Some are just less uncomfortable than others."