Were I you, I’d do what I do here. Here, by the way, is the Willamette valley OR, where it is presumably a bit warmer than Idaho in the winter.
I park my trailer in a enclosed garage, attached to the house, where the whole house gas heater also resides. The garage has not been below 36 degrees in the past few years. Yes, I have a remote temp sensor in the garage. But just in case, before cold weather hits, I blow out all the lines with an air compressor, drain all the tanks, and put some rv antifreeze in the sink and shower traps, drained the hot water heater. And called it good. Easy to do, doesn’t take much time, and I’m confident I’ll be good to come spring.
2015 27ft FC FB
2019 F150 ecoboost