That seems like a pretty good idea, though you should keep an eye out for the heater (if it's glass with filaments inside) cracking or exploding. Throwing in my fish-keeping experience for this one. Fish tank heaters aren't meant to be on constantly/so often or to be used in such severe...
I've heard that putting a water pump in the waterer to get the water moving would help with that? Working on the principle that moving water doesn't freeze. I'm not sure though. http://www.harborfreight.com/264-gph-submersible-fountain-pump-68395.html Something like that? Someone back me up?
Personally, I like getting more "up-to-date" info, and tend to avoid threads that are "dead" (i.e. a year or two or three old). It's not active anymore, so I feel as though if I ask questions in the thread I might not get answers. :)
That aside, I have a 5 gallon bucket with nipples on the...