You could do the same thing....
But put A smaller 12" in there and probably save a ton of Trunk Space. If you truly wanted to do it right maybe some JLW0's or something that aren't in need of a lot of depth. It could definitely be neater, but with the subs he has, it works!
-1983 Grey 528e (Given to Charity)
-1995 Champagne Toyota 4Runner (Friend Totaled) -2000 Black 323i (From DD to Project Car)
-2011 Black Toyota Prius III (DD)