What's the best place to install an amplifier?

Hello, have a 2001 ML430. Looking to install an amp that's about 17 inches long and 11 inches wide (Punch P4004), but can't make up my mind where to put it. I'm going to run my own wires to the speakers in the doors to skip all the Bose amp/sub headaches I've read about - anyone have any tips for running wires under the floor panels? I briefly peeked tonight and saw how the plastic-but-looks-like-metal Mercedes floor panel pops right up, and there are a few screws holding the panel underneath.

Thanks!