When leaving for an extended period with the gas turned off, in a warm climate and hard water, should the hot water tank be drained?

I'd first flush it but then leave it filled

when leaving for an extended period with the gas turned off, in a warm climate and hard water, should the hot water tank be drained?
Not necessary! But you should FLUSH, (not drain) your heater on a regular basis,
For long life and fewer troubles you should keep your heater clear of mineral build-up by FLUSHING NOT DRAINING on a regular schedule.

Attach a hose to the boiler drain at the bottom of the tank. With the pressure on, open the boiler drain and let it run until the water runs clear. You will see a spurt of red,(rust) followed by white or yellow grains,(lime or calcium carbonate). This shouldn't take more then a few minutes.

Do this monthly to keep it clear. Now flush out your hot water lines on ALL fixtures that are affected . Now pull each aerator and clean the screens. Be sure you put them back together the same way you took them out. Don't forget to flush it out every month. Your heater will thank you for it. Hope this helps and thank you for rating my answer,

Tom