Passenger side Tail-lite on '28 Phaeton

[DougVieyra]

As I grow older, and immortality is fading away, I am becoming a bit more safety conscious. Hence, I am now beginning to look into adding a second tail lite (passenger side) to my '28 Phaeton. Because it has a large trunk mounted where the rear spare normally would sit, the existing single tail lite is often times not visible.

So I am soliciting information from those of you who HAVE actually mounted a second tail lite to the body of a '28 Tudor or Phaeton (these are different brackets from the '28 coupe / roadster). In particular, the fit of the new cast-iron brackets, to the body. The bracket that I have does not fit the body as well as I believe it should. Is there some grinding / filing that needs to be done to get a proper fit to the body ?
What have others done to fit this bracket to the car's body, lower belt ?

I would be grateful for any help with this question.