I've been dealing with the same issues (more or less).
Electricity here is very expensive and I've been playing with heating the stock drinker by other means than a de-icer.
Last year I placed
hay bales around the water bowl and it helped tremendously. My electricity bill for February of last winter was less than the year before, and it was much, much colder.
This year I am building what is called a "hot bed". I want the water not to freeze, but don't want
hot water either. A hot bed is a composted bed of layered
carbon and manure, that my drinker will sit in, and I am hoping it will be just
enough to keep the water from freezing. Forgot to mention that winters here can reach -40C which is the same as -40F. I do honestly
think this "hot bed" will work. I am keeping close attention to the whole and will be taking notes on how it works out.
A
RMH may work well if the
cob and pipes go around the exterior of your drinker, but you'll still have to light now and again in coldest weather. But depending on you weather patterns and extreme temps, a hot bed may suffice.
Hope I've been of some help.
K