Run the aircon when it’s hot & cold weather to keep moisture down.
Open the front windows an inch after a minute of demisting to allow excess water vapour out for a few minutes then shut the windows & keep the aircon on.
If it’s icy outside, sit in the car whilst you demist & de-ice as your body heat will help thaw the car out quicker.
I like the damp-traps idea but we don’t have these pound shops in the local town, I think it’s more usual here to employ a chauffeur.