Just a question out of curiosity: Is "over-chlorination" (which in the manufacturers' mindset probably starts at 5ppm) the only reason for the cold water shutdown?
My SWG is quite ancient, and maybe the Aussie models are different to start with, but it never seems to shut off. My water temperatures in winter go down to about 45°F, and the SWG just happily chugs along, run time and output adjusted to maybe 0.5ppm chlorine production per day or less. I quite like it like that, but I fear that once I have to get a newer model, I'll loose that freedom.