Ah, I see now. Your rig is a 45. I had assumed you had more than one and we were talking about a 40. Not surprised it’s a bit different. Well, we have a few options:
You could trim it down with a jigsaw and a metal blade - being carful to protect the finish. I would use painters tape to protect the finish and if your saw is electric run the saw on the inside. A cardboard template would help and I would “sneak up on it” by cutting less than you need to by 1/4” and test fitting before making a final cut. A fine file is good for cleaning the cut edge up. The powder coating should not flake or chip at all and the filed edge should be mostly unnoticed when installed.
Or I could get measurements from you and then make a new one to send you or I could cut one of the two I have here.
