I am trying to figure the best way to mount speakers and amps in my E53. In the past (different cars) I have used a replacement rear parcel shelf with the speakers mounted there. I was wondering if anyone has done such a conversion on their X5? It wouldn't be straightforward as the shape wouldn't lend itself to being freely lifted up when the rear hatch is opened. But with some care I think it could be done.

Has anyone done this? Any suggestions?