We had a rust problem with the storage cabinets on our 2001 Adventurer. Unfortunately we got caught in to many blizzards in Minnesota. A couple of times we had salt softened snow and ice packed solid between the body and the frame. I'll bet there was over a ton of ice slush/ice mix hanging on the motorhome.
Over the years it took it's toll and some of the cabinets started to rust out. We had them repaired with new panels at Forest City. All the panels and framework should be available from Winnebago. As I recall the parts weren't all that expensive.