Future modifications on low point drains. Opinions? Advice?

I see you're from SC, that would explain the questions. The thing is, you can put 12" of insulation around a tank or pipe and if ambient temperature stays below freezing, the water inside the pipe or tank will freeze. You need to apply some heat to the pipes and tank to keep them from freezing. If using conventional pipe heat-tape, you can insulate around that for better heat storage.