I live in WI - outside of the Navy, always lived here or MI.
I've never had a vehicle rust. Including 2 Toyota's. We really don't use salt too much anymore. Some blue crap and a liquid de-icer these days. Raises hell on chrome more than anything but not much chrome these days. Not real chrome.
I just wash the car a lot - underbody flush etc.
The Greenbay area has pretty mild weather.
US41 in marquette county is the most highly salted piece of highway in the state of MI. Untreated cars will not make it 5 years without rust.
Thankfully I moved to a dryer, salt free climate.