Winnebagos are well designed and the build quality is generally as good as any others.
They do things like provide downloadable on-line wiring, plumbing diagrams, and sealant call outs.
They are not advertised as four season units but furnace heat is ducted into the enclosed compartment containing all of the tanks.
I have not seen any motor home I would want to spend a harsh winter in.
Due to family emergencies we have spent several weeks in CO in temps that got down to the teens at night and only up to the 20s in the daytime. We used a heated water hose and a small heater in the service bay and had no problems.
Clay (WA5NMR), Lee (Wife), Katie & Kelli (cats) Salli (dog).
Fixed domicile after 1 year of snowbirding and eleven years Full Timing in a 2004 Winnebago Sightseer 35N, Workhorse chassis, Honda Accord toad