The roof panels are white painted aluminum, which helps keep your Airstream a little cooler in the summer.
The trick to installing the "New Jensen" lid is to use a rat tail file to clean up the flash around the inside edges of the molded hinges on the new lid. This will make the slots a little bigger and remove irregularities, so the lid will slip on much easier.
If you don't already have a FantasticFan, you will probably see the need for one in the near future. In fact, we have two on our 2005, 19-foot Bambi. You are probably using the air conditioner now in Las Vegas. However, when milder weather comes, powered fans give you a lot more cooling options, especially when boondocking. Also, FantasticFans have polycarbonate lids that are much less succeptible to UV deterioration, which is probably why your other vent lid blew off (if you still had the original lids, the plastic probably crumbled into pieces when the spray hit it).
The regular lids only last about one to two years; so if you decide to keep them, it pays to keep a spare in the closet. Unfortunately, unless Camco or the other suppliers have started making polycarbonate replacement lids, you'll probably replace both front and back lids every couple of years.
FantasticFan lids have a lifetime warranty. They probably won't last forever, but the company is great are providing free replacements for a lot of parts that wear out or break in normal use, some of which are beyond the fan's two year warranty. Check out their Web site for details: