Go by a rain barrel and fill it right to the top and drill a small hole in the bottom. Of course put it where you want it first. The slow leak over the root system will keep it nice and moist. If you really wanted you could use cheap tarps or plastic and make a rain catcher on top of the barrel so that it replenishes itself.

No heavy manual labor
No Power,
and no moving parts to break except the rain catcher but if it does there is still the water in the barrel

I'm going on vaction too, but I have a very cool mother in law.