Here are some pics of the new version. Sorry I took so long I have been busy with the new kiddo and getting caught up at work...
Okay, first thing.. If you want I can cut out your tin like so on a punch press. Well this was the first prototype (sloppy). It will look cleaner than this. This is not included in the plate and box just something extra if you want to save yourself some time but I may need your tin as I think I only have one extra now.
This is the new plate with the changes mentioned previously.
Here is the plate set in place on a rear tin.
If you noticed that one screw hole does not line up that is because this tin was the first prototype and I moved that screw hole.
Here are a few pics of the new box. Wiring hole changed to a slotted hole so you dont have to unwire it to remove. Material added on top edge and corners to tighten up some gaps.