[Sternchallis]

If you know somebody who can weld they might be able to fettle it up for you or go to a scrapyard. I notice you are North New Jersey, lots of snow, salt , then heat as well so no wonder its rusted, the scrappers may be the same. I hate to think what Mazda is going to charge for that.
Piece of thin stainless steel attached with the bolt we can see and I assume there is one on the left hand side. Tack the steel to the existing shield and fasten the insulation to that.
Attach the present shield to a piece of wood through the screw holes so it keeps its shape while the new steel is welded on.