I would use wax over Rain-X. Every time I've used Rain-X it pits the glass/plasticso I just take a cheaper wax and throw it on there.

 

ive been planning on getting some seeing as how its been raining ungoldy here....was wondering if it would damage the plastic though.

 

Use wax or just clean your visor with invisble glass, it tends to bead and blow as well as rain-x.

You can actually use wax, or something like opti-seal from Optimum or Clear-seal from Zaino. I tend to stay away from rain-x, not made for plastic but more for glass. I haven't treated my visor with wax or invisble glass yet but it works amazing on my car windows.

Plexus is great too, as far as the fogging they make a fog-x you guys can try out, dunno how well it works though, maybe use IG (invisble glass) on the inside too.

 

I've thought about it... my only problem with RainX is that you have to put it on pretty frequently