I work with this stuff all the time doing all kinds of stuff with it.

If it were me I would buy opaque white 3-M vinyl and put that on the inside. It will last a very long time.

You could take it off take it to a local sign company and ask them to do it. If they are fast and good you should wait and it would be done in about 10 minutes. Should not be too expensive

Instead of 800 grit you can use a red scotch bright pad. That is what we use to scuff the clear windshields on the Baja's with to prep for paint.

Well I have thought about all these ideas and they are good. I have the door back from the paint shop so now it is a default white. I can do some door dressings for cosmetic preferences when I like and this way I always have a default. There may be some wrapping in the future for fun but this season it is white.
Thanks all.