decide where your going to camp mostly. we tend to camp where there is power. since the very effective propane
furnace is a bit noisy,,,and it cycles too hot,,then too cold,,,i find a ceramic cube heater a better option. we rarely use our furnace. the electric cube is quiet, automatic, and cheap,,,,,you already pay for the hookup,,,why not use it.
the only dry camoing I do is sans wife,,,she has a ceramic addiction....
if its really cold I kick the furnace on, but mostly just use a sleeping bag instead.
so my answer is,,,if it doesn't have a furnace...go without for awhile,,,you may decide storage space is more important. oh,,,another option is an electric blanket. 120vlt for hookups...a 12 volt dc bunk warmer you can get at most truck stops,,,for battery