I'm going to generalize that an almost 30 year old rv is not going to fare wet lines and single digit temps well at some point either thru design or some modification along the way laeving part of the system vulnerable to freezing.
Unless you have a good handle on how the system is constructed and protected from cold weather, winterizing is the safe approach.
Couple hundo in extra gas vs a couple hours and $15 to Winterize and a truck stop shower or 2, I'd go Winterize.
2016 Ram 2500, MotorOps.ca EFIlive tuned, 5” turbo back, 6" lift on 37s
2017 Heartland Torque T29 - Sold.
Couple of Arctic Fox TCs - Sold