My humble offerings to the inquiry...just build a simple 3'x4' frame on casters or wheels, so it can slide under a bed...use of a basement or room corner is better...toss some track on that in a copy, or close, of the origonal and "play". I would suggest the use of switches fired via the dynamis, but you might be able to make/find something to make regular switches work{arduino?} via DCC, then your only worries are coupling/uncoupling and trying it out.
If you like what you have- regroup and solidify everything to permanent..if not tweek till your happy.
That's the only problem with On30 is the lack of DCC coupler control for a layout as described...alot of switching...but I'm sure you could work the dynamis, some switch toggles and some coupler magnets via switches together...can't be much harder than running a magazine....you seem the multitasking type.
BTW- if this works we expect a full article about it!...no pressure.