This discussion has reminded me of the book "Sonja's Report", see:-
https://en.wikipedia.org/wiki/Ursula_Kuczynski
This entry says that she trained to build a receiver which she used operationally. I would say that if someone is capable of building a receiver, probably a TRF, then they would have no trouble building a one-lunger TX like the Paraset or using something like the plug-in adaptors mentioned earlier. In this case the lady was working for the Soviets but the above would apply whatever country she was spying for.
73
Roger