You can bulid up the infloor heat and insulation to make it a cold weather unit, not the walls or roof.
We turned a '97 Holiday Rambler 32 WFS tt into a true cold weather unit, not much cost just thought and work.
The HR was already a high end tt with a 4 season rating, Harumph ! . it lacked dual pane windows, infloor heat other than that provided by the propane furnace.
Beware of MFGR claims of reflective films or any other nonsense that increase R value. Thickness of the insulation is the only true value.
To make our HR into a cold weather unit, ( working winters in Canada) I dropped the aluminum underbelly lowered the axles( raised the trailer) ,screwed 1 1/2" PVC brickmould to the frame heattraced all the waterlines with 5w' heat cable and put old thermostatic waterbed heaters on the tanks. Routed the wiring to the inverter so that when on the road the tow powered the inverter, when parked switched it to shore power.
Adding 1 1/2 " to the frame allowed 1 1/2 high density foam and a new underbelly of coroplast.
Windows we dealt with by having a local shop cut 1/4" plexiglass to fit, secured them with foam tape and mirror turn buttons, Next was a dehumidifier because you must never allow humidity from cooking, showering, breath to condense in the walls. We did it through 3 -40f + winters without freezing
Theres so much more ,as in is there a campsite open, can you use a heated fresh water hose, or just fill your fresh tank as needed from the camp freeze proof hydrant? will the cost of propane and elec. save you, will your proactivity be up to snuff.
It was for us Still is.