[Icare9]

Braxton's presence as second pilot would also explain the 8 man crew, with him being aboard to gain experience and evaluate Bomber Commands tactics.
Doesn't help with crash location as yet, but for all to be PoW's including the pilot might infer a crash landing rather than an uncontrolled descent.
The absence of any eyewitnesses from Occupied territories might also indicate the crash was "somewhere" in Germany, rather than France, Belgium, Holland etc.
All just supposition though.