You don't need all that. All I did was cut a piece of ABS plastic and hot glue it to the back of the GXE kit.

Pic:
http://www.eden.rutgers.edu/~nbalani...a/CIMG1030.JPG

 

You can go to a install shop most installers have ABS scraps sittin in their tool box throw em 5 bucks or something. I used to use left over dash kits or trim rings and just a lil hot glue it in like dj said.

Edit: Looks good in there nice deck!