Good call, geezer.
I've carried Lemon Pledge wipes while touring. That stuff really works well on windshields, including laying down a very thin layer of polish that works the same way Rain-X is supposed to -- helping rain bead up an roll off. Doesn't hold up through a real gully-washer, but works pretty well.
Right now I've got one of those pocket-sized cans of Plexus for touring, but when it runs out, I'll probably be back to the Pledge wipes.
For my helmet visor, I just use the very diluted soapy mixture that comes with a Wee Willy.