I'll take a shot to try to help you... Now, mind you, i'm in Virginia so the "winter months" are just a little bit different.....
Be prepared to use A LOT of propane for the furnace.... suggest getting at least one portable plug in space heater (we have two for really "cool" nights).
We usually camp right up to Thanksgiving time... and we've had nights in the upper 30's, two space heaters going and occasionally the furnace would kick on, but not run for a long time.. and we all would be comfortable..
The furnace will provide some heat to the underbelly... hopefully enough nothing freezes on ya!!
Blankets are your best friend also... keep plenty on hand....
Also... don't forget about the hose line warmer... or purchase a "heated hose"....
2010 Tundra DC SR5 TRD 5.7L towpkg (gone)
2008 F350 Lariat CC DRW 6.4PSD
2013 PT Tracer 3200BHT
BlueOX SwayPro (used when hauling cart too)