My workshop is just around the corner of Lambeths salt mountain so the road I park in is salt dust all winter, so I take off the alloys & put the steels on until the volksworld show. regularly powerhose the underside.
I'm gonna be using mine when I'm not working on it! I think as long as you look after the underneath by washing all the crud off every so often and keep all the chips touched in and protected you stand a better chance of it lasting longer
I use mine in the winter the cold is not to much of a problem you get use to that they main problem i found was window frosting on the inside and outside of the windscreen while driving...haha
I live on a small island so the sea air takes it's toll on my bus all year round. I just make sure I underseal the chassis every year and keep an eye on any rust issues on the body. Never had any problems so far.