22Mustang

I have purchased a floor pan for each side of my car, but once you get to the underside of the actual back seat there is rust spots. I see that with Real One I can replace offers a full truck floor that covers the rusted area. I guess what I am looking for is the area that is under the back seat or should I make some cold steel replacement pieces? Can someone help me with this problem or give me some ideas plz.

Thanks all