Richard, I think you'll find that the space where the second reversing light should be is actually the rear fog. Its a clear reflector with red LED's.
I agree with you on the build quality. My 250 certainly feel better built than the 300. Now there's a thought, it's still in my garage. Perhaps I could palm the 300 off to my buyer and keep the 250 ! That would solve my rear fog problem !!!!! Only joking, just like you I also think the 300 is a great car, different and more fun to drive.