John,
Thanks for your input. My plan is to put toggle switches on every siding. Other than that, I'm pleased to know that you agree this plan should work because I prefer to just use 1 TIU. As I recall, when I met MTH at Train Fest, Dave (I think that was his name) said it was okay to use jumper wires on both transformers to stack power to a single TIU and power all loops as one and use the DCS remote to control the layout. That seemed extreme, so I thought it might be better to run the 4 throttle handles of 2 Z4000s into the 4 channels of the TIU (2 fixed, 2 variable) for a cleaner distribution of power. That also would give me the option of actually using throttle handles instead of the remote to run those loops.
