To save disturbing him you could leave him in his hutch, keep a kean eye on the weather forcast & its going to get really cold move the hutch somewhere: garage, outbuilding etc with electricity supply and just use a small tubular heater to keep frost from the immediate area he is in.
I used to hibernate mine in a concrete garage & sectioned off an area at the back with sheets of 4 x 2 x 2" thick polystrene from Wickses diy. (Its tongue & grooved so holds together nicely) torts were double boxed in usual way & i only had a 2 ft tube on a thermostat, just to take the chill off not get too warm. (I placed the boxes in a "u shape" around the heater, so none were directly in front of it or too close. I draped old blankets etc to block any gaps...it worked very well
Dont forget: its colder on the floor, warmer up on a shelf ( but must make sure box is well closed & secure if placing on a shelf for a while)