Update - May 2023
I have finally completed the design for the new space. I have a 16x30 area, with 16x24 available for the layout, and the rest for a crew lounge and workspace. The space is clear, the lounge and work area is set up, and the materials are on-hand to begin construction of the modules. The idea is to construct modules 4-feet long by anywhere from 12 to 30 inches wide. These will bolt together and to the walls, allowing me to deal with smaller sections. The modules have to come from the shop, through the upstairs kitchen and down to the basement. I do not have direct access to the basement from outside.
Each module will have a 5mm plywood top skin, with layers of 1 or 2-inch insulation foam board to build up the landscape. Track sits on 3 or 6 mm thick cork sheet. Mainline track is code 83 ME flex-track with a mix of Peco, Walthers, and hand laid turnouts. I'm using Central Valley tie strips and turnout kits for some detailed foreground scenes with ME weathered rail.
The layout is a twice-around point to point design, surrounding the walls with a center peninsula that hosts a "shared" engine terminal and the yards at each end of the district. There's a hidden cutoff to allow continuous running. I'm going to try to use "vertical staging" with three 2-track shelves on a panel that slides vertically. I will drive this with a motorized jack-screw. This will provide two through tracks plus two shelves that raise/lower and provide four 6-foot storage tracks. I might also procure some trackage rights under the stairs for additional stub-end storage.
Click on the images below to open a full-size image of the layout and module design. I'll post photos once construction gets underway. Alongside the layout diagrams is a photo of the Crew Lounge. I built the lighted engine display cases to fit the space in the built-in bookshelves.

Loco Roster

My currently active loco roster.