Most of the silvering inside the reversing light on our 2007 Troll had disappeared. Yes I could have bought a new one, but I found on Amazon a Chrome marker pen. I had no idea such a thing existed, but with judicious use of a bent cotton bud the silvered surface inside the light is now as good as new.
The only disappointed party…Mastercard.

I have recently found a chrome paint that really does look like chrome when it dries - Go Chrome paint - not cheap, though...