Question?

The cab area needs to be closed off during extreme cold. I had Insulbright covers made for all windows, vents, skylight, front cab, and side door. Storage becomes an issue.

I know I will start a war but I'm totally sold on dual pane windows in any type of camper and won't have one without them. In Nevada, even in the summer, nights can get cold and unlike your house, in a camper you are usually sleeping less than a foot away from a window and a single pane will let the cold air slide right down onto you. No drape, curtain, or blind can take the place of dual pane. Just makes for a much more comfortable living space when it's cold out. Class C's don't really have any insulation in the cab area so a quilt to close it off is a good idea. Or, you could bite the bullet and go with a class A. Rarely come across people who are sorry they did that rather than get a class C. While the class A has a big single pane windshield, you are generally not sleeping close to it so the front curtains minimize the discomfort from it.

The premise you've been given is too broad. As said above, it depends on what brand, model, construction etc is being compared to what. Another poster above referred to windows etc being 'bad' on their C. OTOH, mine has dual pane windows and zero drafts and nominal temp transference. I think most would agree that the cabs have whatever insulation is provided by GM, Ford etc and that it's minimal but my cab is closed off when I'm camped so it's isolated and not an issue. When you shop, it will pay for you to look beyond the glitz and bling and look at mfr specs on issues like insulation?? Those specs will be far more authoritative than a bunch of opinions on a forum?

The cab on a class C is poorly insulated. We got a snooze bonnet, close the curtains, and make sure the heater vents are closed and the fan is off before turning off the engine.

Our Sunseeker has 2" walls. We camp in AZ in the winter, when nights are sometimes in the 30s, and usually in the 40s. We've had nights in the 20s. It's pretty good. The windows, door, and vents are bad, just like all RVs.

The cab is bad too, but all you need is a good quilted bedspread or similar to block the cab off.

Ours is small, 25', and it does not take much heat to keep it in the upper 60s at night, which is where we like it.

I believe it has more to do with which model / brand you buy rather than style.

Bill

I have had Class A, B, C, TT and FW.

No difference to me.