Andy, the module construction looks very interesting. Have you ever posted the construction technique? The table tops seem wider than most modular construction and the legs remind of Mianne benchwork construction even though they are obviously different.
Our modules start at around 32" in depth and go as deep as the owner wants and can carry (mine is 48" deep). Basic modules are 4 feet long, but we have and use modules that can be up to 12 feet in length and as short as 2 feet in length, not counting smaller filler pieces we use in odd-shaped layouts like Kennywood.
The legs are just 2"x2"'s held together by leftover plywood or scrap wood with eye-bolts installed in the bottom end to use for leveling. The legs are attached to the modules with floating-board clamps built into the underside of each module. You can see this in the following pix:
We use polarized 2-prong plugs to carry the track power around the layout, and most modules also have a 110v in the back to allow accessories and small transformers to be plugged in as needed.
For normal 1-2 day setups, modules are just clamped together and we adjust and shim the ends of the track as needed. For Kennywood, because of the duration of the event, we take the extra measure of pinning the modules together so that we don't have to constantly adjust track as modules shrink & expand due to temperature changes (the building is heated, but was never insulated -- the heaters were installed just for us when we moved from the cafeteria building).
Here are pictures from our work session last night where we built a new yard module. In the pix you can see the basic frame, installation of the luan plywood, routing of the edges and velcro groove in the fascia boards, installation of the fascia boards and chalk-lining the track locations. The track will be installed later, on site at Kennywood.
Andy