There is an answer. I do not know why Roman did not give it. You will need to utilise SDC with the basics of TCI set up and the Macro server tab open.
1. Make your recording(s) using on/off line recording to wave file in ESDR2. Do not convert to mp3.
2. In SDC with Macro enabled and set for Use In SSB, have External Window checked.
3. Use the external window, called Macro 1, to load the wav file. The cog icon top right of Macro 1 does that.
4. Press F1 in the Macro 1 window and your radio will transmit the audio file over the air.