Since I too think the Yaffe plate frame would draw too much attention from the local police up here in NH, I think the Kuryakyn frame is the way to go. However, like others I too prefer just the frame without the additional chrome piece at the top. So I have designed and fabricated my own custom back plate.
Here is a photo of my second prototype for the back plate. This one is cut out of 1/8" stainless steel, which the final one will be. The first was cut out of 1/8" mild steel for proof of concept.
The second prototype allowed me to get the custom tooling I created for bending the back plate to exactly match the curve of the Kuryakyn license plate frame, part number 3144. This was not as straight forward as one would think, as once the tooling is used to bend the back plate in a press, it springs back after the pressure is released. And the amount of spring back is different between stainless steel and mild steel. Hence the need for the second prototype to be in the final back plate's material.

This one also allowed me to ensure the tapped 1/4 x 20 holes used to mount the Kuryakyn frame were properly located. And to make sure the countersunk holes for the screws would be flush behind the license plate once the back plate was mounted to the fender.
Unfortunately, my bike was dropped off at my dealer and put into storage before the Kuryakyn license plate frame was available. So I cannot check to ensure the countersunk mounting holes are properly located or that I have the correct amount of offset from the fender mounting holes and the Kuryakyn frame. I want to have the plate mounted as low as possible while still covering the hole in the fender for the wiring.
If anyone has their bikes available with the license plate and back plate removed, I would love to get some precise measurements of the mounting holes, from center to center. And the offset from the mounting holes centerline to the top of the wiring hole. If not, I will just have to wait until spring to finish my custom back plate.