WRG,
How you approach that depends upon your power and control system and what your layout is on.
I have a layout on tables which will be on LCCA\Lionel Modules when I build them. I covered the top with felt and run the wires under the fabric. I will just drill holes on the modules. Move something...new holes, fill the old.
My lighting and accessory connections will use male\female connectors for quick connections for setup\disassembly.
All of this is convenient because I have an 8 wire buss running underneath. I can get various types of power and ground anywhere. This is the foundation for the variability that you need.
The temporary nature makes scenery more of challenge. I have to make my mountains and tunnels lightweight and portable. They are also different for the home setup versus the travel setup.
I will most likely be building dioramas for a scene with buildings and such on a separate piece of base material that can quickly be set in place, connect the wires and it's ready to go. That way the buildings, trees, people, roads, etc.(all of the elements) are affixed permanently) while the scene is portable.
I hope this may give you some direction to get some new ideas to accomplish what you want to do. I'd be glad to share details if you like.