A couple of other things to consider regarding motor heating:
The ESC - if the esc has a low switching frequency, it will tend to heat the motor more. A Vantec has a standard switching frequency of only 300 Hz, which will result is more heat than necessary being generated by the motor at part throttle. The new Wottys are around 12 kHz IIRC, which results in a resonably smooth output current at part throttle. Much better. The IFI Victor/Thor is especially bad in this respect - only 75 Hz.

Another thing that has a big effect, of course, is how much throttle you use. With reasonably powerful motors (e.g. Bosch or better), you should be able to get wheelspin at low speeds at half throttle or less. Using more than this generates substantially more heat in the motors, without any significant increase in thrust. Learn to be gentle with that throttle.

Ive being trying to get myself to back off the throttle in the last couple of fights (Boschs at 33V are a little marginal), and its surprising how little you need.

Also note that gyros can give the motors a hard time, especially if the gain is turned up, as they can send frequent large bursts of power to the motors to maintain course.