I liked this idea a lot. So when I was installing my subwoofer I built a storage drawer to go underneath the new floor panel that I made (because the existing floor panel is way too thin to bolt the subwoofer..

I cut a piece of 3/4" plywood to fit the floor in the cargo area. then I covered it with carpet that matches the factory material and color.
I bolted my subwoofer unit to the new floor panel and put it on top of the storage drawer. (The old floor panel is still in the original position covering the storage area beneath it.)



I put blocks on the underside of the new floor to interlock it to the storage drawer.



The cover flips up (with subwoofer attached), clears everything, and can be propped open while accessing the stored goods.