I used to keep two of the waters you're talking about. I'd keep one inside, and one outside and twice a day I'd switch them for unfrozen water (and the frozen one would defrost inside in the meantime).
Now I don't do that. I just bring other containers out. But it doesn't stay that cold where I am that long or I'd probably do something different. As it is, I have to be outside twice a day at least anyway.
I do have a submergeable water de-icer for the cattle though. The chickens tend to drink out of that and the other water containers all over the farm, so I'm not as diligent about keeping the chickens in water anymore. No, I'm not a bad chicken mama, it's just that water is all over the place here.
I like the idea of the electric dog waterer, but I don't like having too much electric out. I think I'd still be bringing out fresh water twice a day.