Hi, JD-EE
I will start now and continue later editing my answer:
1) The HF antennas are not located in "no conductive VS".
2) They run near and in PARALLEL to metal. Much better would be at right angles (like the 707 Collins design)
2a) Correction: They RF excite the VS in a "shunt configuration". A driven thick wire is connected to VS at an height ranging from 3 to 9 ft or so. This is not the "main" antenna. But radiates (when transmitting) some of the energy because of high RF current circulation. Iy actually supply RF energy to VS. Can be considered part of the coupling circuitry (Z match).
3) The signal to the rear IS MUCH WEAKER simply because no "return=ground plane" behind VS.
4) Drag for a trailing short wire (letīs say 60 ft) i donīt think would be a problem. Ok, you have APU, etc. But iīm not advocating the use of the System Amelia Earhart had in the Electra or the reel wire in the C47, etc. What you say about trail a 30,000 ft like the 707/CFM56 of USN for subs? Ok, it oscillates and USN paid for a damper for it,
To be continued...
Rgds, appreciated in commenting