Every time I drive over a bump that flexes the body slightly at low speeds, I hear a loud plasticky creak in the rear cargo area. I've tried removing the cargo shade, tried folding down the seats, re-arranging the seatbelts and even tried driving with the rear hatch open just in case it was the hatch flexing while shut. I've even taken the entire spare tire assembly out. Nothing has worked. I'm thinking it's an issue with the sunroof flexing or some sort of trim panel in the back. Anyone have the same issue and know of a way to remedy it at home?