So about the cooling and thermal management of the motor, the above is the plan. Actually, just to enumerate some of the possible ways to prevent overheating:
1. Use reduction gearing to reduce torque required from motor
2. Oversize the motor
3. Use forced air cooling
4. Active thermal management/control, with motor temperature feedback (using a thermistor or similar)
5. Most importantly: lots of testing.
I think in the end there is a large range of motor sizes available, and the power to cost ratio of these motors is really good. So getting the right motor shouldn't be a big problem. After I get back to a proper workstation after the holidays, I will make a spreadsheet to help people pick motors for their application, and include some motors I recommend (and of course have it so people can add their own motors).