When I was wiring new houses in extremely cold temps, I had 1,000' of wire warming up all the time. I knew what wire I'd be pulling the first part of the day, so I'd put that in the cab of my van on the way to work so it was warmer when I get there. When I got there, I'd take that wire out and put in another 1,000'. At break time another 1,000' in. Lunch time another 1,000' in
Just two hours worth of wire at a time. Warming it up just 15 or 20 degrees will do a lot to keep the sheathing from cracking.
As far as the boxes breaking, I'd suggest hitting the nails only. Or use front-nailers.
Here in the KC area, nobody uses plastic boxes for new houses, everyone uses fiberglass. Doesn't matter if it's winter or summer, miss the nail and that box is trash.
There comes a time when you've just gotta come in out of the cold, though. I never had a problem nailing boxes, drilling out, or pulling wire because I was constantly moving. But boy, when it was time to stand still for several minutes at a time making up 3- and 4-gang boxes, I was really looking to go home