I took a piece of .030 steel I had and riveted it to the package tray front edge / lip , and through the floor on the bottom.
I cut out around where the seat mounts would stick through and used seam sealer at the edges of these and on the sides.
The seat back pops in like normal and you can't tell.
You have to cover the speaker and vent holes on the package tray as well , and I did.....but how close it gets scrutinized depends on who is working in tech when you go through.
Since you can't hear the radio when it is running anyway , it wasn't a big deal to close them off for me.