I'm about to get my electric car back on the road and due to the lack of A/C and almost no cabin heat it can be hard to keep the windshield fog free so one thought that I had was to install a dehumidifier in the car, behind the seat and plug it in to the spare plug from the charger plug so that it would come on whenever the car was plugged in.
A google search came up with two decent options dehumidifiers for RVs/cars
EDV-1100 Eva-Dry Electric Petite Dehumidifier that are also targeted at keeping closets and under sink cabinets dry, the other option is kind of like the silica gel filled sock, only in a fancy plastic case.
Amazon.com: Eva-dry EDV-E-500 Renewable Wireless Mini Dehumidifer: Health & Personal Care