The reason I say don't drive before the sun is up and until the air is heat up is not because I worries for you to drive in pitch black darkness.
Cause during winter period there is something call black ice due to frosting. FYI, black ice you cannot tell by seeing cause it look the same like road, and if your car go over it. Bye bye.. enjoy your flight...
Slow how slow is your slow? FYI with snow chain you can only drive 20~30km/h only. So you will drive at this speed early in the morning?
Tell me which area you want to drive at 7am and I can let you know it is safe or not.
O For all who is going during winter, prepare for plan B cause if Southerlies come with heavy snow, all the road will be close and you can be stuck. Also prepare food in your car at all time, there will be cases you are on the way when snow storm hit and you will be stuck on the road for the night and have to wait for rescue to come.
Should you really get stuck on the road and have to stay in the car for the night. Please off your car engine, take out all your cloths to cover yourself warm. Wind up all your car windows to keep inside warm. And when inside the car start to get too cold then on the car engine and turn on heater for half~an hour then off your car engine to preserve your petrol, cause the night will be very cold. I'm got into this kind of situation before, my car is always loaded with winter sleeping bag so not much of a problem for me.
Here is some fact news report
https://www.youtube.com/watch?v=9erEo1SqbZw