This is a view of my shed where "The River" will be situated.

The shelf above the bench will be removed and two 4m x 70mm x25mm  steel beams will be fixed approx 100mm lower than the shelf, so that the top of the layouts are slightly below the height of the window at the far end and at a suitable height for viewing.

The layout will be on two 600mm x 1200mm base boards connected at the middle and joined to the helix's at either end.
This will allow for removal and transportation to exhibitions or storage while other layouts are being "worked on" or "played" with.
As I envisage doing a Dwellingup-Etmylin  logging layout as well as The River, the steel racks and helix's will be fixed and the "modules" can be easily installed and operated.