Does anyone know how to patch rusting out of a truck? The worst spots are around the wheel wells and under the doors.
The reputable repair places won't try replacing the affected areas because too often they can't find anything solid to weld the panels to.
I wish I knew more about auto body. Where I live in northern Minnesota, our roads are salted all winter long. That leads to rust issues on metal that you never see down south. I have some perfectly good running vehicles, but they look like, well, not so good anymore.
I have seen that there is some kind of rust stopping paint. That might be a first start for some parts of the car. I think you put the rust stopping paint on the rust spots and then you can paint over it with whatever color you want.
I had a relative who had some bad rust around the wheel wells, so he hit it with some rust stopping paint and then bought some fender wells to cover it. Looked really nice when he was done. Of course, the metal was still rusted under the new plastic fenders, but his pickup looked nice.
I know our local body shops won't do a job unless they are allowed to "do it right." That usually means replacing entire side panels, etc... You can quickly get a cost estimate for more than the value of your older, rusty, vehicle. No such thing as a cheap makeover in the body shops where I live. Their shops are mostly filled with insurance repairs, so they don't really care about the rest of us that just want to make our old cars look as good as they run.
Many years ago, I "fixed" up some rust on one of my cars by sanding the rust spot down to bare metal, then used fiberglass and bondo to patch the holes. More sanding, sanding some more, and then a number of light coats of primer and paint. In the end, it looked good, but it was a lot of work.
There are a variety of YouTube videos on fixing up rusty cars. I would suggest checking them out and maybe find one method that might work for you. Some of those guys do great work without breaking the bank. Good luck.