On top of all that, if you are worried you will be away for a very long time, you can ensure the traction battery is at "full" capacity (that being around 80% of total capacity).

This is how:

Place the car in drive, then firmly apply brakes, then at the same time apply the accelerator to bring the engine RPMs up. Watch the energy management screen to see the flow of power from the engine to the battery, and when the battery is full, release the accelerator.

I don't think this is needed, and would just waste fuel, but it is a way to force a charge into the traction battery.