Determine if they are worth saving first. If your travel trailer or RV skylights are not too damaged and just faded there is a way to add some life to them and make them look better.
First, using a soft bristle brush and soapy water scrub them thoroughly to remove the white oxidation. Be careful and don't apply too much pressure since a faded RV skylight may crack or the brush may punch all the way through.
Prepare them for painting. After the RV or travel trailer skylight has dried completely use blue masking tape (which is easier to remove) and mask a one foot radius around the skylight. Now you can paint the RV skylight with special plastic spray paint.
Using Krylon for Plastic Glossy White spray paint begin to apply even strokes of spray paint to the RV skylight. If the surface is severely faded it will be very porous and the paint will soak in rapidly. One skylight could easily use a whole can. Apply an even layer to the plastic skylight, not so much that you get runs and allow it to dry. Apply more layers over the course of a few hours. Once enough paint builds up to cover the pitted surface of the skylight the surface will appear glossy. In a week or two you can spray on some Protect All silicone RV roof protector.
This method will save you several hundred dollars that RV and travel trailer skylights cost and prolong their life for a couple more years.
