My last winters - got sick of starting out with a cold car. Not even a 1500 watt block heater did much. So I purchased a special LPG heater that fits a radiator hose and circulates. I used a Magnatek (this was many years ago) ferroresonant charger to keep the battery up. Bypassed the defroster fan motor. When it got to -40C The cab was +15C along with the engine. I spent a lot of money blowing foam into the voids of the cab. Finally I said the heck with it and abandoned ship. Cold places are for the young. Old people mimic iguanas.