Mounting amps on E70 with 3rd row seats

[masq]

I hate that my X5 has every option BMW offers, EXCEPT for premium sound. Okay, well that's not really BMW's fault so I'm ready to upgrade using some of my equipment I have from previous cars.

In preparation, I've poked around, studied the cabin, and pulled my hair out trying to figure out where I could mount a couple of amps that I have that are about 15"x8"x1". If I had a spare tire compartment, I'd be okay with just pulling out the tire and mounting the amps in there. But with my 3rd row seats, that's not even possible... nor is it to build a custom enclosure that could sit flush in the cargo area wall and allow the seats to ever be used again.

So does anyone have any better suggestions?