This is what I would have:
Aux diesel water heater to keep the motor warm enough to start.
Aux diesel air heater to keep you warm.
Winter tyres and a 4x4 wheel drive.
Insulation for the popup roof and for the windows.
Arctic sleeping bag.
Snow shovel, and a brush to keep the snow out.
Empty the water and waste water tank.
Engine antifreeze coolant.
The 907 butane gas bottle probably is difficult to use in those temperature conditions.