This is a tricky one to answer; it'd *still* be tricky if I were standing there looking at it and using a ETG!
Some marring is too deep to be safely removed. I tend to err on the side of caution as I believe "better imperfect paint than a need for a repaint".
But if you're working *without* a rotary and the strongest thing you've tried is #83 and you're working on something that has plenty of clear to start with (hasn't been rotaried-to-death previously) then you can do a fair amount of polishing without having to worry too much.
It sounds like you're using pretty mild stuff so far, so I don't think you're likely to have taken off much clear.
Note the abundance of qualifiers in the above
Yeah, I'd take #83 to it myself, well, actually I'd rather use something like Hi-Temp Heavy Cut Leveler

Maybe three-four passes and then something milder to clear up any micromarring. Then I'd probably live with what's still there, at least for now.
OK, if it were mine I'd go at it with the rotary first and I'd use Extreme Cut, so I'd actually be *more* aggressive than that. But I wouldn't have to polish it again for a long, long time either

so I'd be OK with taking off more clear now. I don't recommend that you get that aggressive.
Unless (or "until"

) you have your wash/dry regimen scienced out to where you don't have to polish out wash-induced marring on a remotely regular basis, I'd stop at that point because you'll be polishing again in a few months anyhow.
FWIW, I've had a few of my vehicles as close to marring-free as I can imagine drivers getting, but even those had some marks lefet over. Marks that I could probably take out, but didn't. I'm just not gonna risk compromising my clear's long-term durability. I'd try to resist the urge to attain perfection, just try for "much better". Sometimes this forum can sorta seduce you into thinking that every car can be perfect all the time and that there's something wrong with driving something that isn't ready for Pebble Beach