In addition to salt/sand mix, New England states now also use Pre-Mix (Sodium Chloride/Calcium Chloride blend). Which is likely even more nasty for your vehicle.
Some of you may not understand; there is no using outdoor plumbing at your home in winter. When it is 4 deg F for weeks in a row, you cannot turn on a spigot or use a hose, etc.
Everything freezes. Period.
You use a commercial car wash when/if you get a day above 32 deg F...and I have not seen one that will accommodate a dually.
I do know of one that spins around you as fpoole mentioned above...IIRC they do not wash the chassis. Which is a major concern for me.
I would hate to spend $60k on a new dually and turn it into a pile of rust...