Learned more about comic storage from Dale during a tornado than I did in five years of collecting, which honestly says a lot about me.

That 500 rule thing got me too, I wasted a whole clear night in my driveway shooting 30 second subs at 200mm and every single frame had trails you could see from space. Columbus lights are brutal for this stuff so 15 seconds at 3200 was a smart move on your part. One thing that saved me when my old laptop kept choking on DeepSkyStacker was shooting dark frames right there in the field before I packed up, because without them the stacking makes the noise look ten times worse and you end up with a muddy blob instead of dust lanes. Also check that you turn off in camera noise reduction and image stabilization, those two settings alone ruined my first three attempts at M31. Four nights is honestly fast for a first keeper, it took me about six weeks of on and off trying before I got something I would show anybody, and even then the core was blown out. Keep at it, the next one gets easier once you have your settings locked in.