What kind of rv and truck do you have? I have a 99 E 350 coupled with a Triple E Regal and that has a dash operated rear house forced air heater control. Heat vent is located on the bed framing at the rear. I drive in wold weather with that cranked open/on and the house stays warm as anything you could ever ask for.
And yes, for sure, that furnace while you are on the road. These things are designed to operate in those conditions. Say the pilot light gets blown out? The gas is shut off, it doesn't just continue to spew out.
Gary Haupt