I think you're fine to begin organizing and you won't freeze your battery unless it's discharged. FWIW a fully charged battery could freeze at neg 92F and a battery discharged 40 percent could freeze at neg 16F. So it's possible under extreme conditions, but just keep it charged and you will be fine using it now.
The xpower 1500 is basically a 51Ah AGM with an inverter and outlets so could help you in a pinch or if you wanted to run the micro for a bit.
DW, 3 Kids and our Goldens
2012 Shamrock 233S
2008 Toyota Sequoia 5.7L 4WD