[Mrmerlin]

I like the idea of clear coating the plastic after its been polished never tried it though.

I have done some polishing of headlights with compound then swirl remover using a gray waffle pad it works pretty well.
I would not use wax on the plastic as that will possibly damage the surface and increase its susceptibility to fogging.
Though plastic polish seems to work well,
I would suggest to not use anything other than car soap and water to wash the covers