I have the masterlock but I taped it with black duct tape to keep it from rattling and wearing the paint. I figured that if i needed to take the tailgate off i would just peel the tape off to insert the key. At this point in time I have no reason to take the tailgate off so its been okay for now. But I could see if i did not tape it that it could get corrosion and be a potential problem.
I too wrapped it in thick gorilla tape, hoping to protect the paint. It was less than effective from a long term standpoint and ended up making the whole thing a gooey hot mess. I hate tape glue, personal peeve.