Class As in cold weather?

That's not true with a diesel coach with Webasto/Aqua Hot heat. You can stay plenty warm and the wet bays will stay well above freezing for a long time. The heating system uses the fuel in you tank so you have plenty available for extended cold periods.

if its going to go below zero its going to be tough to keep the water system from freezing no matter what you get you will need a auxiliary lp tank and enclose the bottom at the least check utube for videos of what it takes to survive those kind of temps

We've been in cold temps in the teens with our Bay Star and stay quite warm and toasty. I get enough heat from the gas furnace in the water bays to keep them from freezing, but I have remote temperature sensors in the bays and have two small personal electric heaters that can be turned on if necessary. The Bay Star is well insulated. When the temperature is closer to freezing or above, I use an electric heater at times to help save propane as I'm usually at a campground with electric service.

We don't winter camp, so our experience with cold weather is usually when we head south in the winter and have to travel from Ohio to wherever it's much warmer!

Class A diesel units are going to have some version of Aquahot diesel fired baseboard heat. This also heats the wet bays and keeps everything nice and toasty. If the unit you look at does not have this then pass. All the plumbing in inside the coach so even if it got really, really cold you could add a small electric heater or a light bulb or 2 to the wet bays and you will be fine. We have traveled in most every weather you can imagine and we have been fine. I must say that when the company sent us to ND in January (20 below zero) we passed and drove our car and stayed in a hotel!

We have run both our furness and dash heat. Our dash heater is fed from the engine 40' away.. we do run the block heater in the engine to keep the engine warm for start up

So it may be slow to heat up on cold mornings.

Tell him when Co gets to cold you have room for him and his in the class A parked in your side yard.