OK.I went back to 400, 600, 800, 1000, 1500, 2000, compound (admittedly crap turtlewax), polishing compound (twax again), and then Meguiar's plast-x.
In some light it looks really great, like here:
...Except where there's a haze that I think is from the lacquer thinner attacking the plastic when i was stripping it. this is the spidery haze visible below on the right side of the 'hump' in the flyscreen or at the top and bottom edges of the screen.
Mind that when i was stepping up the paper this hazing was always there, even when i could see it "under" sandscratches from the paper i was using (confirmed by changing the orientation i was sanding in and watching the sand scratches follow).
I scraped at it in one place with a knife (ruining all my sanding, i know) to see if i can get to clearer plastic underneath and that seems to have worked? Do I just need to sand these areas til i see the hazing gone because i hit "good" plastic underneath?
BTW: I realize the buff/polish is not perfect (you can see circular lines) and i get that,but it's "good enough" for me if I can just get rid of the haze.