Buying first TC, want the "perfect" used rig (cold weather)

We have a 2008 Lance 861 which has the dual fan heater (kicks on a higher BTU when needed) and like every has said, propane will last a couple of days however without solar, generator or plug in the batteries will go pretty quick since the furnace pulls lots of amps. We love our 861. Huge holding tanks for a short bed camper with a slide out. 36 fresh, 30 grey, 33 black!