Wonderful progress, John. I'm still envious at having such a large and beautiful environment in which to build. In the spirit of helpful pitfall avoidance I offer this as addendums to previous suggestions.
I would highly recommend the addition of some form of leg height adjusters that make direct contact with the concrete floor. Otherwise, when the table sinks into the carpet as more weight is added it will require constant readjustment. Direct table contact to concrete keeps kneeling to a minimum.
The sliding disc method should be employed with all things moveable along the carpet floor. Dolly wheels just create resistance and leave divets where they rest.
A concrete track plan is needed now. Before a sheet of plywood is laid, take a break and at least solidify a plan for your mainline on paper. Sidings and spurs can easily be added on the fly if necessary.
And here's my own inspired suggestion. To save many unnecessary wiring trips down under, consider the cookie cutter roadbed design table top. Feeders and other electrical connections can be threaded, soldered or fastened from up top long before the scenery is applied. Having a carpeted floor and this type of roadbed would be the ultimate in layout noise reduction.
Bruce
