Here in Norway, road salt use is extreme, probably like some areas of Canada. A local company has developed a set of additional covers to install, that will cover this area, the big open rust trap area up front, and various other exposed places. They install it together with doing a treatment using Fluid Film products. It gets quite messy under the covers due to the Fluid Film, but *zero* corrosion issues. Re-treatment every two years to keep it effective. When that is done, they offer a lifetime warranty against rust damage. (not surface rust, which will at some points occur anyway)
Model 3/Y rust protection Check this here out to see what is done here. In Norwegian, but I guess you catch what it's about by watching the video anyway.