A proof of concept trial has started to see if the batteries and CNVRTR chips can be tucked away in trailing cars. A small path had to be cut in the chassis of each boxcar for the two wires from the locomotive. The trick is to test the ease of accessibility of popping off the body to load the battery and connect it to the locomotives each session. It's not real convenient with these boxcars, but doable for the near future until the more permanent plan is in place.
The plan is to model and 3D print the maintenance of way cars the HBS actually used on a regular basis. There was a flat car/transfer caboose looking thing and street sweepers that were regularly run to keep the flangeways clear of debris at street trackage.
Edit: I should have mentioned that there is no problem with radio communications to the receiver in a plastic box car.