Wow. This is a great forum indeed. I wasn't expecting such good and quick feedback about the questions I raised.
gwl - in the Saris Bones 3 rack that you used to have (to prevent the bikes from banging) did you put both bikes in the "slots" closer to the glass of the tailgate, like "bike-bike-empty slot", or did you alternate the bikes, like "bike-empty slot-bike"?
Is the visibility of the license plate and taillights a problem where you live?