The vinyl decal is adhered to a thin sheet metal backer. I don't remember if I was able to buy the sheet metal or just the decal.. someone with more experience can chime in on that.
Here are the two pieces separated, in this case showing a bad glue job:
I think your best answer is to replace the sheet metal backer. If it isn't available as a part, there is no magic to it except cutting to shape without bending.. get some strong (cold-rolled) aluminum or steel sheet and cut it with a dremel or similar method that won't bend it.
I do know the metal sheet came off my bezel with some prying, as it was glued on.
I used a strong contact cement to bond the new sheet metal in place:
Your bezel plating looks to be in good shape!