ID try using some rubbing alcohol (70% isopropyl) diluted with some water to try to lessen any etching or "clouding" of the plastic.
I worked in a hobby store and have quite a bit experience with plastics. If you go to a hobby store you may be able to find a super fine sandpaper kit that will remove scratches from plastic. The sandpaper is down to like 10,000 grit or something so it is quite fine. JUst work down from like a 1000 grit paper or so(dependingon the depth of etching) This may work for you as a last result.
Goodluck!
Jeff