Oh - another idea was to build some speaker enclosures custom out of wood, put 2 speakers in each box, and cover the sides of the boxes with the same type of material that's on the back deck. On the front, I'd cover them with a household type of speaker grill - black linen basically. I was thinking to make the boxes triangular, and have them point toward the dome light (well, straight ahead, but focus them to point midway up the headliner). I could probably get some 6" in there for bass. A summer project!