Last weekend we did our first winter camping trip for some backcountry ski touring and visiting friends skiing at a resort 5 hours up the road. It was great, but obviously heating/drying out stuff was tough. I had my small 1000w honda generator running a small space heater (on low) and a small buddy heater running before bed, or during breakfast. Nothing running during the night, mainly for security on the generator and even with a CO detector, wasn't a fan of the buddy heater running over night (being a voly firefighter and chemist). Condensation was a problem.
For not wanting to spend anymore money on your unit,you already have the best alternative..To dry out stuff you need radiant heat such as the buddy heater or a wood stove...I use the buddy heater/catalytic heater when I snowmobile which much like sking,requires things to be dried out and the camper warmed up.Combined with the TC furnace,it warms up quickly..
With catalytic heaters cracking windows is important especially for condensation..With the direct radiant heat, which acts like a wood stove sorta,it makes drying out things easier but really wet stuff needs time to get them completely dry...I heat my house with a Blaze King wood stove and wet stuff needs time, even with it.
Another option is two honda's or one larger generator to run an electric heater on high...Candle type heaters do take the chill off but don't do much at -10..Kinda like the light bulb in the water pump area or under a skirted RV to keep the tanks from freezing.
I sleep with radiant heaters going when it is really cold..I crack/open the window several inches next to the bed as does my wife..Short of wood heat,a radiant heater is your best option...The Wave 3 heater would not do the job in sub zero temps in my Lance TC and that's with all the little things added for that weather.That's why I went to the small buddy heater,more juice..Combined with the TC furnace,it heats up quickly...
Another option is the old forced air furnaces,some like one model of the Atwood, only draw 1.6 amps off your battery,others are in the 3 amp draw area..The really old ones didn't use a fan and were true forced air furnaces without battery consumption...
Winter camping is a lot of fun but there is a learning curve for each RV and there weak spots..No two seem to be the same..