From what I have read so far....the posters before said solar and that's a fact.
I see that you have a pretty exposed system tho. I have no idea how much effort would be involved, but any way you could wrap the pipes with some of that insulated foam piping from Home Depot/Lowes. That's what's gonna kill ya. The tanks will be fine to about maybe 25, but the pipes...that's your weak spot. That and the pipe connections. There is a heat tape, but then you have to use power to keep them working.
The fan motor on your furnace is a real power pig. Keeping the rig at 60 all night long, while you guys are sleeping, is not needed. You might be ahead of the game to get some good warm bedding and then flip a coin to see who gets up to make the first coffee. And your inside pipes won't freeze up and bust.
And just a hint...even if you were to wake up one morning with no juice..open the oven door and light'r up.
Gary Haupt