When I installed a Tomahawk luggage rack on my 04 KP, I had to cut down the license plate holder about 2.25".
It was an hours work, had to cut both plates down, re-drill about a dozen holes. This ended up about 1/8" below the luggage rack. I left it straight up, so the light would not shine in anyone's eyes. It could have been laid down, but matching the mounting holes may have been more difficult.