[gearhead]

I don't know anything about the Springdale, but I can tell about the Montana HC. Our salesman's pitch was that the "Polar Package" was tested at zero degrees (I think) for like 24 hours and nothing froze. I was laughing at him during his oration, but he kept it up.
Living near Houston on the coast, it's big news if the temp gets below 30. So at the time I thought it was irrelevant anyway.
The Montana HC has the chloroplast cover screwed to the bottom of the frame. It has insulation that looks like bubble wrap on the backside of the chloroplast. I have a small (2"?) furnace duct that terminates near the black tank drain. That's about it.
I used the 5th this January for 5 nights in overnight temps down to 15. I had no issues. I had all the storage bay lights on and 2 trouble lights in the bay with 60watt bulbs on as well. I found water lines that supply the washer/dryer near the storage bay door so I put some slip on foam pipe insulation on them. I used the electric "fireplace" to supplement the furnace. I also used an electric blanket. I was concerned about running out of propane but used only half of one 30# bottle.