Hi Joe, thanks for the quick reply.
My two TIU's are older models (no USB port, not rev L).
That's a great point about burning out the lighted switch. This is an area where I'm a novice, but in the case of the switch that I linked above, it says it's rated for 125 VAC, and that the bulb pulls 12VDC. Would the bulb or the bulb's wiring in the switch burn out in that scenario? I'd be pushing 18V from the transformer in this scenario.
If lighted switches won't pull enough power, or if they'll just burn out, I think I may have to hunker down and build a bunch of filters per Susan's schematics. Hopefully it's not too complicated!
Thanks again!
Rafi