Discounting accidents and health, mechanical failure is about all that's left in the trip stopping department. Being prepared to deal with that is dependent on how good a bike mechanic you are and what tools you carry.

The obvious:

1. In addition to extra tubes, carry a spare tire.
2. Spokes and tool. Or a Fiberfix temporary spoke, if you can find one. They seem suddenly scarce.
3. Cable ties.

As long as you start with a mechanically sound bike, with components suitable for your load, the odds of a trip stopping failure are near zero.

Should the freewheel/bottom bracket fail, the tool for getting that fixed is your thumb or your feet.