John - I was thinking of hacking an R2LC. I could either just look for the 455kHz signal or do something with the detected command data. It would be connected directly to the base as I just wanted to see if the base was up and running. I am impressed with all your hard work on the buffer. Dale was a genius and it's hard to believe he is gone.
At one time I proposed making a TMCC receiver using sub-miniature tubes. I have loads of these in my vacuum tube collection. There is no valid reason to do this except, why not?
CJACK - that would work in some scenarios. Inside rails would probably work too. Perhaps use an accessory track.