BUT, instead of heading the rest of the way off and stopping the car where I could see oncoming traffic before reentering the track, I looked in the mirrors (I was still up to speed and didn't see any cars, but with halo seats and a Hans device, I can't see much behind me) and drove back on.....close enough to an oncoming Cayman that the driver had to take evasive action

I knew I screwed up big time, the black flag was redundant at that point. Needless to say, my next action was to head in to the CDI's to receive a richly deserved - and expertly delivered - *** chewing. Only my Hans device prevented me form bowing my head in shame.
What's the point of this tale?
It's that once the "Red Mist" settles in, sensible judgment suffers no matter how experienced the competitor, and like recurrent flight training, we have to renew our focus from time to time.
It also points out that as instructors we suffer from not having other instructors ride with us to catch our bad habits because we always have enough beginning students to keep us busy.