Looks like this broken tail 'trim tab' might have caused the crash in Nevada. Trimming at LEAST 3 feet from EACH WING surely resulted in lift problems as well.
I will assume that you did not look at the NTSB material because they stated clearly that the trim tab came off 8-9 seconds after the incident was set into play. Therefore, the trim tab, which you keep pointing to in the picture, was an effect of the original incident and not the cause.
Lets face the facts!
Some Unqualified and Amateur Butchers altered this P-51 drastically and fatally and No One including the FAA certified the drastic Changes!
Then a 70 plus Pilot (who might qualify as an Egomaniac) was allowed to fly it at excessive speeds that he braaged he would do, within feet of an unsuspecting and innocent crowd of Thousands!!
Thanks be to GOD that Thousands were NOT KILLED and MAIMED!!
And before You;al flame me, I am a forty something year Licensed ATP Pilot! I LOVE the Air Races!! Lets get some Brains behind them NOW!!