I did a December cow elk hunt here in MT. about 15-16 years ago. Friggin cold. Got down to -20 at night and I was camped out with 10x10 spike tent with a little Riley wood stove that would produce enough heat for about 20 min. before stoking again to maintain heat so obviously didn't last through the night. Had a good sleeping bag but regardless, in those temps a guy learns quick how to prioritize and organize for the little things in life, like taking a crap without freezing certain extremities. All good fun!
On similar cold hunting trips, I do the old trick of filling a Nalgene bottle (or 2) of boiling hot water and sticking one down by me feet, in my sleeping bag, and one up near my core.
Plus I keep an empty bottle close at hand to pee into during the night, so I don't have to leave the tent. Taking a leak in freezing temps,after crawling out of a warm bag is no fun at all.
THE CHAIR IS AGAINST THE WALL.
The Tikka T3 in .308 Winchester is the Glock 19 of the rifle world.