The brochure for the 2007 Tour Master series of diesel coaches lists an "arctic package" but does not detail it. On my coach, the windows are all double pane (except the windshield and cab area ones of course) and the mirrors are heated. The tanks are in an enclosed heated basement, and the engine has an electric block heater. There may be added insulation -- but how would I know?
Other members here may have more specifics, and you can always ask GS themselves...
2007 Tour Master T40C
Acura MDX toad
"It takes a great deal of time to recover from any improvement..."