That's easy to fix. There's two things you could do.
1) Get yourself some silver or black Rhinoliner. Roll it on, be done with it.
2) Get yourself some spray on Duplicolor rubberized undercoat. 4 Bucks a spray can at your local auto parts store.
Spray it on, making sure you put in cardboard or some other masking between the rocker panel and the rocker panel protection plate. Let it dry. The undercoat is black, so it will contrast with your truck's body and match your truck's top.
I'd attach a picture of my rubberized undercoat, but since my truck is black to begin with, you won't see it....
-Steve.