I wouldn't give up on the Windex before trying it with newsprint. Don't use paper towels as they have perfumes and softeners in them that leave residue. Even
Windex wipes leave stuff behind. If you can stand it, you can try ammonia instead of Windex, and again with newsprint. I've had bad luck with Rain-X on a previous car - disolved the wiper inserts, leaving black smears.