I had that with my volvo. I had two subs with an amp in between and a capacitor mount. They were all attached to a piece of MDF that I had stapled carpet on. Whole thing would slide right out. I most likely wont be taking it out that often at the moment. Just need half the trunk for now. Hardly ever have more than myself a backpack and a tool set in the car.

That dude has a nice Bimmer. Ive been going spool crazy with the Fiesta ST lately.