Dave Stinson pointed out an important but lesser known application of the TBY.  Dave, I will say I am interested, but my interest and attention may have not aligned with your previous posts.  Your scholarship is appreciated here. 

I have been distracted from radio by child rearing, work, medical crises but experiencing a rebirth of time and interest due to a short period of being unessential during COVID, and the fact that my kids have grown up.   One of them is a USMC communicator.

I have used the TBY ashore to communicate with the TBS on USS MASSACHUSETTS.  That interoperability as Dave pointed out is important.  Merchant ships in convoy were able to monitor and participate in comms with Naval vessels running TBS sets. 

TBY to TBY communications are a more likely application of the sets in the real world as there are few TBS sets on the air.  I have also made scheduled QSOs with a ham friend on 10m AM where he was using vintage ham gear with a wide and tuneable receiver.  

The TBY ground plane was used on landing craft, which I think is specifically mentioned in the manual for same, which I may still have.  It may have been used on merchant ships, but I think the references I have read talked about going out on deck to operate the TBY, which suggests the whip antenna.

RF