We attached a single layer of 5/8-inch AC plywood to the hat channel, which gave us a solid surface for attaching our storage casework.
On both sides of the box, the storage cases rest on banks of drawers, which provide enough elevation for the casework to clear the wheel wells and the fuel-filler pipe cover.
The drawer bases on the passenger side are 24 inches deep, but the storage carcasses on top are just 13 inches deep.
This depth is enough to accommodate the Systainers, with extra room at the front for our "high-tech" securing system—lengths of ½-inch electrical conduit that slip into holes drilled in the top and bottom of each carcass to prevent the cabinet contents from falling out if we take a turn too sharply.
We completed the sheet-goods rack with a shelf that sits 50 inches above the drawer base supported by a cleat on the wall of the truck box and vertical strips attached to the backs of the storage cases.
The floor of the rack is at just about the perfect height for us to slide sheets into while we're standing outside.
The shelf above cantilevers beyond the side of the rack to accommodate larger Systainers, and we added a fiddle rail around the shelf to keep everything in place during transportation.
We make a fair amount of flashing in the course of installing windows and doors, and having a brake in the truck lets us make the flashing right on site instead of having to run back to the shop.
The carcasses on the driver's side—both the drawer bases and the storage cases—are 20 inches deep to permit storage of larger items, such as the compressor, shop vac, and table saw.
We also created a large cubby on this side for a stack of Systainers mounted to a dolly. These contain the tools we use most often: a cordless drill and impact driver—usually the first things we need at a job.
Next to the cabinets on the driver's side, we left room for a metal mechanics toolbox. We took the wheels off the box and secured it to the truck box. The toolbox has drawers of varying depths, all of which are mounted on ball-bearing drawer glides.
We built a miter-saw station above the cabinets on the driver's side. Having the saw inside the truck allows us to do our cutting in a sheltered area out of the weather and keeps dust in the truck, minimizing cleanup as well as disruption to our clients' homes.
Directly behind the front wall of the box, we built two large vertical cabinets. The one on the driver's side was left open—we store dust poles, levels, and other long objects here.
On the passenger side, we took a different approach, carefully laying out the cabinet to accommodate specific bulky equipment that can be a challenge to store. These items include step and folding ladders, a pair of work tables, the stand for our portable table saw, and a handful of moving blankets and drop cloths.
Partitions for this cabinet are ladder frames that we made in the shop and then pocket-screwed in place. If we should ever need to change the configuration of the cabinet, we would simply back out the screws, move the partition to its new location, and drive the screws back in.
Other than the custom cabinets for the Systainers and the work stations, we tried to make use of every available surface for hooks and holders for items such as extension cords and pneumatic hoses.
I also mounted the holsters for our heavy-duty caulking guns on the rear face of the cabinets. I even added a dry-erase board at the end of one of the cabinets so we can jot down notes about any items that we need for the job.