Rust vs. Alero

[TheEdgeofSanity]

so, i knew it would happen sooner or later because my car is 10 years old but I feel like in the last year, my car suddenly hit a "self-destruct" button and is rusting apart! It's not really visible but my trunk lid latch has rusted off and I repaired it with some stainless steel bolted in place and the paint on my driver quarter panel by the taillight is bubbling up but thats the least of my worries. This past weekend, my power steering blew a line and I am proud to say I successfully fixed it myself this time, but getting under my car for an extended period of time allowed me to see how terrible the underbody of my car is doing! here's the problem areas I have seen but don't know how to prevent from further damage:

exhaust shield by cat is literally hanging on by 1/4 inch of rusted metal, all attachment points are rotted through or mostly gone

both driver and passenger rockers are rotted out, I peeled up the plastic trim in the door jams and there's barely anything metal left under them (explains why my carpeting gets wet on its own when driving in rain)

the exhaust manifold shield on the engine is rotted out around two of the bolts that hold it on (i thought this was aluminum??)

bottoms of doors are all rusted on the inside lip

So, I know many of these issues I have to live with but is this happening to everyone else? I know I live in Michigan that salts the shit out of the roads but I am insane about washing my car and rinsing the underbody. I don't know what else i can do to slow down this process. I was thinking of coating all super bad areas with rust neutralizer and then a coat of rustoleum? after all its under the car so nobody would see it?