Hello Mike,
I see you use the thermostat for the same reason, we don't live at our pond&cabin either(someday i will). It sure has been a cool summer, we had 44 degrees on aug.13, but the trout are happy.
I guess losing fish to predators is part of it, i just saw my first Herron on the pond a few days ago, he was standing on one of the floating islands probably picking off frogs. he's probably been there before, but i didn't see him.
I'm not sure if i want to use the thermo. in the winter like you are, or just run it nonstop.
Are you planning to raise 10lb bass like Dwight in Minn.?(Aquamax with ball bearings)!!!