trust me you are in for s surprise. rockers mostly rust from the inside, i have seen 3 sets of rockers been replaced and the inside look 100% worse then the outside flaking rust chunks laying in the rocker and all, but the outside only had a few little bubbles and spots.
i took a wire wheel to my rockers on my 03 and they also only had a few bubbles then the wire wheel went through the rocker and creaked a 3"x1" hole i tacked a piece of steel behind it and bondo'd it because i had no money.
also all you peoples dissing Canada for salt, i live in BC and they do not use salt here only sand and that is only for the whole week that we might get snow.