Heat pumps won't work in Wisconsin? Sure they do. Here's the rest of the story:
Heat pumps exchange heat from the air outside and put it inside, just the opposite of air conditioning when it takes heat from inside and puts it outside. There is a limit to how much temperature difference can be accomplished by the standard heat pump/AC unit. When a heat pump is using outside air around 35 degrees or less, it just can't extract enough heat to keep it 70 degrees inside. That's about a 35 degree difference. If you've ever been in an extremely hot environment, say 125 degrees or so, you know your regular AC can't cool you down to 70 degrees either.
So what do you do for heat? If you're in an area where it gets colder than a standard heat pump can extract enough heat energy from the outside air, you add heat strips, electric resistance heat, to the duct work for the heat pump to augment the heat supply. These can be added to home units and to RV units. The heat strips come on as needed to keep your house comfortable. The heat pump still provides the air movement, responds to the thermostats call for heat, utilizes the ductwork to put the heat where it's wanted, etc. So, your heat pump does work in Wisconsin IF it has been engineered to work in Wisconsin.
Ned is right when he says his heat pumps won't work in extremely cold weather, mine don't either, but it's only because they aren't set up to work in cold weather. They'd work just fine if they were equipped with heat strips.
My Arizona diesel fuel will start to gel in Wisconsin winters too, it doesn't mean that diesel fuel doesn't work in Wisconsin it means that I need to adapt my fuel.
Ken