many of us use a ceramic heater or a oil-filled radiator heater to supplement the trailer's furnace.
you can set the thermostat lower so that the furnace only kicks in when it gets below what the ceramic/radiator can maintain, therefore using less propane.
unfortunately, we rarely get to use ours or the heated mattresses since we dry camp almost all the time.
and Zoe the Wonder Dog(R.I.P.)
'07 Roo 23SS pushing an '07 Chevy Avalanche
Equalizer WDH and Prodigy BC