Looking for the best option for rock slider coating. Previoulsy I sanded,rubbed acetone, primed with Rustoleum etching primer, and sprayed the Rustoleum bedliner spray, and there was some rust showing through after last winter in Michigan primarily where the bolt holes are. I have a quote to piwder coat for $325 locally. Any thoughts on if this will hold up better with salt in the winter? Is Linex better? Thanks