Size is NEVER a guarantee of better insulation. Only better insulation is a sign of better insulation. You need to know the R value of walls, floor and ceiling plus provide information about how holding tanks and storage tank are heated and how the drainage system is prevented from freezing. These are the MAIN features that determine how well your trailer will perform in a four season situation. You MAY be just fine but if so it won't be because the trailer is larger than another one.
For what it's worth, your furnace ALWAYS runs off of 12 volt power (battery) and ALWAYS uses LP Gas to provide heat. All the 12 volt power does is operate the thermostat and the blower motor. IF you are connected to 120 volt AC power, that is used to recharge your battery.
Good luck / Skip
