I would like put a furnace in my gooeneck car trailer that i use for sleds. I want want a ac one that i will connect to 500 gallon tank and plug in to land power. I want heater in the neck of trailer. Looking at a suburban P-40. My ? is about intake and exhaust vent. Not seeing a heater can it sit up there and i use 90 elbow for vent and exhaust and go straight down with them instead of out the side of trailer? Or do they have mount up to a wall for air. I have plenty of room above that could you use house furnace and duck off the top back. Thanks