I have similar in my 500 Pop and first thing this winter the inside of the windshield was always frosted over. To help minimize, always run your heater in AC position, instead of Auto. If you have the manual controls, turn on the AC. (When your car is on defrost, the AC will always come on.)
The AC will help dry the incoming air, and crack a side window slightly to let air escape. Try to carry as little snow/water inside the car as possible. It's not perfect, but it does help.