My 97 E320 parts car came with ice scrapers ( new ones to boot ) wedged in both rear doors. Given they didn't hold the window up too well, I ended up wedging a 1" X 3" piece of carpet between the interior window sweep and the glass. ( carpet side towards the glass ) This can be done without taking anything apart, use a door wedge to make room for the carpet.

The car is stationary so no report on how long friction will hold it up.