Eddie, thanks for mentioning your PVC solution to this problem. I have an entirely different issue but this may do the trick.
I have a Big Foot. The upper corner marker lights
are so close to the radius corners that the flat base of the marker light
overhangs the corner, leaving a space of about 1/2". I will try your PVC board to make a base with a radius of 7" then leveling out flat. What a great possible solution.