installing a radio in a damaged dash
 

The prior owner of my mustang cut out the dash to install an aftermarket radio. I want to put a Custom Audio USA6 in. I've found a repair plate that u can get n either plastic or metal. I really do not want to install the metal one since u have 2 weld,bondo, and paint. But the plastic one would look jakey if u just glued it over the hole and painted it. i wuz wondering if i could instal the plastic repair piece on the inside of my dash. Then buy another one and cut it to the size of the hole. Glue that to the 1st repair plate then bondo and paint. Anyone know if this will work?