John....Yes, Winnebago has cornered the market (in my opinion) with the mass produced assembly line motorhomes, with one of the strongest roof structures in the market. They are definately known in the industry as having "weak" insulation R-values, although they're structurally solid.
They offer dual pane windows, they should also offer a "Winter" package. Winnebago upgraded the basement air to a larger capacity for 2009 to offset the low R-values, so they could at least offer (as an option at least) a Winter package.
My 2001 HR Vacationer had 8 layers of various insulation in the roof, and 4 in the sidewalls....STANDARD.
Just a thought! (hint!)