I leave a n old plastic cup outside. I poor cold water over my windshield when it gets ice or frost on it. You could also use a large piece of cardboard over your windshield before you go to sleep at night. If you have the money, look into buying a car cover.
I had a big problem with this in the city.Towels stick.An old guy a couple of houses down told me,come out in the morning,turn on the motor to warm up the car,adjust the heat inside the car to the interior rim of the windshield setting.Then go inside and fill a tea kettle with hot water (not boiling,just hot from the tap) .Pour on windshield.Presto.No scraping.