Many moons ago I used to drive cars like the original Mini, Renault 5, Renault 14, etc. that did not have AirCon and windows fogging up was always a problem in cold/humid conditions. Then I got a BMW 320i (1986 I think) which had AC and I soon learned that if you leave this on all the time you did not get misted windows ever (except perhaps for the first minute or two when you start the car from cold), the heater and AC worked together to keep the cabin both warm and dry. Ever since then I have always left the AC permanently turn on, I have never turned it off on any of the many cars I have owned since then. Of course, I live in the UK and so this may not apply in other less temperate climates, and yes, I do realise this will affect my MPG and Wh/mile but that is price I am willing to pay for the comfort and convenience.
I sometimes see cars being driven with misted up windows and I know that that model of car has AC, as most do these days, and I just wonder!!!