Actually I have been thinking again about the custom woodwork idea. The price of cabinet grade lumber is steep these days but I am coming around to that as possibly the only solution that I can get accomplished.
Along those lines I started to do what a modeler does when frustrated and build a model of part of the benchwork to give me an idea of what I would need to have cut.
The attached photo is a 1 inch = 1 foot concept model of the benchwork section C on my plan. It would be the largest of the sections being 30 inches by 72 inches. The plan would be (harder to get) 1 X 3 or 1 X 4 wood for the L girder and 2 X 2 legs. The lower strengthening pieces would again be 1 X 3 or 1 X 4. Note that the L girder that is in back by the wall is reversed. This section is 6 feet long and 30 inches wide. The height is 36 inches which allows for up to 4 inches for 1 X 2 cross pieces and 1 or 2 inch foam sub roadbed to reach the maximum planned modeling surface height of 40 inches.
There are no grades in my trackplan. I plan on using a 1 inch foam as the basic line and adding another 1 inch foam that can be cut out to provide a little surface elevation relief and allow for the turntable depth.
I am looking for stability and rigidity more than mobility. All wood pieces would be attached by screws. It could be collapsed back into a pile of cut lumber when I need to move out.