Near to freezing or slightly below freezing is a stretch to "Sub-Zero" temps... Additionally, to say "stay in below sub-zero no problem" Well then I do have a problem with it. Number one is burning thru propane. Knowledge level is equal to every degree below freezing. Lots to prepare for and understand to stay in a 5th wheel below zero degrees.
One of many available to help prepare...
Don & Dona W/yorkies Gizmo, Master Chief, & Tali
2011 Flagstaff 8528 BHSS 2015 Ford 6.7 XLT
2010 Full Timers & Still Going