To finish the enclosure, I glued 2" tall feet to the bottom to give the Mags plenty of room for excursion. Here are the enclosure and amp rack installed into the truck (still need to wrap the enclosure with carpet - still deciding what color to use as I'm going to reupholster the interior in short order):
Here's the final wiring off the battery using KnuKonceptz battery terminals and Monster Cable 1/0 to the KnuKonceptz fuse block (3x100amp mini-anl fuses) to a Monster Cable 1/0 to 3x4ga distro block:
From the distro block, I ran 3x4ga KnuKonceptz Colossus Fleks to the amp rack (1 to each of the 1kD's, and 1 split with the KnuKonceptz distro/fuse block to the 50.4's):