If you can get through the coating, the novus products work with buffing. #3, #2, #1. I had a bad gash from an oak branch.. deep. I buffed off the coating and did the Novus in the right order. It's not perfect but better. I use Plexus too and similar products. I use microfiber to wipe and I even keep my windshield wiper on the machine because lexan attracts dust as you know. It's not a pefect solution but it helps. You can get all three Novus for about $28 US through Amazon.
I've gone through this for years. After awhile, lexan is just junk because without the coating, the UV light yellows it if you can get the majority of your deep scratches to where they don't hold dust and refract light the wrong way, you will get more life out of it. Feel free to PM me.
BTW. Plexus has anti-static properties and is a must have in the toolbox but you have to use microfiber to apply it and buff it too but it only takes about 4 minutes to do a big windshield. I use it inside on the undamaged side to keep dust from being attracted.