Not sure of relevance to the HF thing, but don't lose sight of the fact that a KC-135 is not a Boeing 707 with a boom and a paint job. It's a Boeing 717, with a separate development line from Boeing's original Dash-80 demonstrator. As the company's "717" designation did not feature prominently in marketing, Boeing decades later felt able to re-use the number for its legacy Douglas/MD DC-9 offspring.
Amongst other things, there are significant dimensional differences to a 707.
Respect and sympathies to the crew in this incident. Is it just me or, futher to the loss of life, the loss of something as graceful and majestic as a Stratotanker (or Nimrod, or Victor) make these events so much more tragic?