Last year at the Midwest contest at Verne's field I checked Andrews temp just as the plane stopped rolling and it was just at ambiant + 2 or 3 degrees, but the longer it sit there the hotter it got. Whitin a couple of minutes it was up to (and I'm working from memory 6 months old) top of 130 to 140 degrees. So to me if you run a proven setup the temps in the air is way cool for the motor. What I think and this is just speculation is that after the plane is stopped heat is coming back to the motor though the wiring from the batteries. Would be interesting to unplug the battery and see if the motor temps still go up, if you could do it fast enough, even better if had plugs on the ESC to motor to check. Should be noted that Andrew has ducting to put most if not all incoming air over the motor.
Steve Maxwell