Just some thoughts when reading the foregoing. These bridges have already been crossed by Lionel, at least to some degree. Fairly recently, Lionel converted their Vulcan snowplows from Pullmor motors to can motors. This Rio Grande can-motored version (there was a Pennsy as well) is equipped with TMCC as well. (The Pullmor powered PWC snowplows, and some other Vulcan units, I think, had TMCC as well.) In any case, Lionel has now done these Pullmor-to-can engine changes in smaller units.
My other thought, speaking of putting the electronics in a following car, was about a few small units Lionel has made, such as the NYC Fire Car. These are TMCC equipped, with sounds. Since there wasn't room in the engine, Lionel pull all the electronics in the trailing boxcar, with a tether connection. I have one of these, and it works very well. (Actually very cool with its siren sounds and flashing light.)
