I had the perfect marine-layer day to try out timthom62's sunglasses lens idea today. One lens did not work; I might try a doubled lens tomorrow. But I'm definitely keeping the electrical tape idea in the back of my mind . . . thank you, brent!
And you people who find this discussion ridiculous [I'm looking at you, FrostedG] can just go on your merry way turning the lights on and off manually while the rest of us try to figure this out.