Then I started on the amp rack:
Layed out the amps to determine how I wanted them to be positioned (both for aesthetics as well as easiest separation of power and audio wiring):
I marked the board, drilled the holes for amp mounting and wiring, and then shellac'd it to add some measure of weather protection (this is my winter 'beater' after all :lol

:
I then covered the board with a heavy material with a PVC backing, mounted the amps, and ran as much wiring as I could without the rack being in the truck: