Thanks, Jim! Here are some final before and after pics. I finished the rear window, and looks like I dug myself out of a hole successfully on this one. I threw the steel wool away lol. I did take things off a bit, but the cerium oxide finds its way into every nook and cranny. So, time to give the truck a bath anyway...
It turns out the good ol' Dewalt with a 3" wool polishing disk was way more effective than the DA polisher, which I didn't expect. I used the finest cut foam pad on the polisher though, and didn't apply as much pressure. But, I'm done experimenting glass! All the water spots are gone, the fog from removing the water spots is done, and I'll calling it a day!
Before:
After: