I have a 2017 SG that had the same problem as the OP, brushing against the rear cover and screws gave a lot of noise. Finally made a fix that seems to be permanent. I had a conductive plastic box that was about the same thickness and texture as the rear cover plate, cut a new plate out of that and installed it so a bare spot on the ground wire was against it on the inside. No more noise. In a previous life those boxes contained static sensitive parts and were thrown away by the dumpster full, I put ohmmeter leads a couple inches apart and get like 50K ohms resistance so it is fairly conductive stuff. It wouldn't take much for Gibson to add a bit of something that conducts to their plastic formula to eliminate this problem. Yeah, its shielded now, but more than that, static no longer builds on the plastic surface and discharges in to me. A guy with more ambition than me could probably make decent coin on the bay making these....
