Tom,
You should note that the recognized stylist of the Pagoda, Paul Bracq, went to BMW in 1970 and designed the first 3-series, 5-series, 6-series, and concept 7-series, in addtion to the 1600Ti...
Go to any auto parts store and you can get mounting brackets in a variety of sizes and kinds. Mine is simple and holds the rear plate about 1" away from the rear sheet metal. Yes, there was some drilling involved. Consider stainless steel hardware.
The local independent installs "rivnuts" in the rear for plate mounting, avoiding brackets. These are rivets with a threaded center section that can take screws.