There is a 'heat tape' used by people in cold climates, but it requires being plugged in. I guess the principle is that it keeps plastic pipe (or any pipe) at about 40-degrees, so not hot enough to melt, but warm enough to prevent freezing. Of course that would require good electric outlet access.I know there's no way of keeping that all thawed.
Could you modularize it? I had thought of starting pipe with a 5-gallon bucket. Maybe not fully automatic to match your vision -- but maybe having to only fill multiple 5-gallon bucket(s) with a garden hose, easier than multiple waterers? Just Brain storming here.