scratches

I had to use ratchet straps to secure some cargo on top of my tonneau cover on a recent road trip, and they've left these markings on one flank. At first I thought it might just be dust that would come off in the car wash, but that hasn't worked. Any ideas on what will work?

I realize that this has been discussed in other posts before, but I don't believe we have a post specifically discussing owner's perspectives/beliefs regarding the truck's long-term durability. Granted, much of this will be speculation, as the only real way to test this is to let time take its...