I don't have to worry about compromising the "quality" because this new-age "sanding" rattle can primer doesn't block. You cannot touch the stuff with sandpaper without the paper instantly loading up.

The best game plan that I have come up with is using a #150 grit foam sanding pad from wally world and water. So what I'm doing is going from #36 grit on plastic to #150. I don't use finer grades on plastic because I have a tendency to undercut the plastic before I can feel out "straight." With sanding primer, it has never been an issue in the past. One or 2 hard #80 blocks, and you have the foundation for super straight bodywork. You cannot do it by skipping the #80 block because it's the most critical part of the foundation. So good enough will have to do.

I have some areas that have been buffed, and they aren't super $hitty, but as you had seen before, I'm super anal about a straight body, so anything less sucks. It'll be good enough for whatever life has in store for however long, and it looks a thousand times better than large rust holes and deep surface rust.