OK, so I finally found a few spare moments to get this done.
First, this is where the idea started:http://www.tvsjr.com/truck/1_rcm.jpg
The box in the center is the Restraint Control Module, or RCM. The surrounding bracket is dual-purpose - a stiffener to protect the RCM, and a mounting point for the factory console. You can see two of the four bolt holes (threaded) on the driver's side.
The RCM was an initial oh-crap moment... we weren't quite sure how to deal with it. After some consideration, we came up with a plan - to build a flat floor that would support the consoles and various other gear. Some more thinking gave us the additional wire chase idea.
At long last, this was born:http://www.tvsjr.com/truck/2_floor.jpg
What you see is a piece of 3/4" MDF with some very custom cutting work. The front half-round is an entry point for cabling coming from the dash and under-hood. As the truck floor falls away from the board, it leaves room for cable to enter.
The two ovals in the middle of the board are dual-purpose - slots for cables to enter the "chase" area, and access to the back side of the mounting points. Rather than trying to use the factory bolts/threading, we elected to use bolts that would pass all the way through, then added washers and a nylon insert lock nut. This ensures a very stable attachment.
The indentions you see in each side allow the seatbelts to move with the seat (goal was full factory motion of the seats). You can see the edge of the runners, which are pieces of 2x3 lumber stood on edge. These runners are contoured to the floor, so all the weight is transferred to the factory floor. The runners are doubled up in the rear, as the floor falls away and needs more wood to fill the gap.
Taking a big jump forward, this is wiring (excuse the mess - there's a lot of stuff in there, as you'll see) in the forward console. In the middle, between the two nylon wire-tie strips, is one of the access slots with wiring running through. Prior to install, the base was covered in indoor/outdoor carpet (if you wanted a more factory look, you could use color-matched stuff designed for car audio) and a piece of carpet was laid down in the wire chase area to ensure no chafe points existed.http://www.tvsjr.com/truck/3_openconsole.jpg
Here's a closeup of the passthrough:http://www.tvsjr.com/truck/4_passthrough.jpg
Now, on to the end of the chase:http://www.tvsjr.com/truck/5_chaseend1.jpghttp://www.tvsjr.com/truck/6_chaseend2.jpg
The Stridsberg multicoupler is sitting on the flat floor, pictured earlier. The audio combiners are sitting on a standoff, across the top of the wiring coming out of the wire chase (we installed a piece of 1/2" plywood underneath the rear seats to help with all of this install, plus the pure-sine inverter under the right-rear seat (you can see the power and ground 4ga. cable on the top of the first picture). All of the wiring is secured using the same strips, then it all runs to...http://www.tvsjr.com/truck/7_hole.jpg
The Big Hole.
This is a 4.5" diameter hole cut in the rear of the cab and front of the bed. We then installed a piece of large (tractor-sized) inner tube loosely between the two, screwed to the wall on each side. This seems somewhat low-tech, but it provides a weather-proof passage for a large amount of wiring, and still allows the frame to flex without compromising the wiring. We've done this several times with nary a problem, even on high-mileage vehicles.
That big pile of cable runs to the rear board:http://www.tvsjr.com/truck/8_back.jpg
This is a combination of two pieces of 3/4" plywood - the bottom attached to the bed and the top to the front superstructure of the ARE DCU commercial topper. The front of the topper leans forward slightly, thus the two-piece design. All of this equipment will be protected by a carpeted board installed in front of it - the board rests in a piece of C-channel along the floor, and attaches to the side boxes using 1/4" bolts (see one in the top left corner).
Up top: Whelen Cencom, Whelen Alpha22M (controlled via the Cencom using custom firmware). Barrier strips are termination for the Cencom, Alpha, various lightheads, and other point-to-point wiring. Power distribution in the center - A+, master 1, and master 2 (two-stage master switch to control all equipment... *everything* is controlled by the master). Right side is large power distribution - handling 1/0ga. power and ground from the front, over to the second battery installed in the right side toolbox, with isolation provided by a Kussmaul Auto Isolator system.
On the bottom, all the radio decks.
All buttoned up:http://www.tvsjr.com/truck/9_console1.jpghttp://www.tvsjr.com/truck/10_console2.jpghttp://www.tvsjr.com/truck/11_console3.jpghttp://www.tvsjr.com/truck/12_running.jpg
The pictures aren't the best of quality - blame that on my iPhone. Hopefully it gets the point across.
If you get serious about doing a similar floor, we may still have the schematics around. PM me and I can try to pull those up and get you a copy.