If your phone is prone to crashing, I would fly it on Solo to be honest. This results in no aircraft or ATC needing to load, resulting in a smoother experience.
If you want it to be online, I’d say Expert. The only reason that I can see that you’d get any violations is if you ran out of fuel.
I think I am leaning toward Expert because I want realism, and also I will be awake for the last third, so I can monitor fuel levels and plan a possible diversion. Restarting my device before the flight will also help right?