Despite 55x900s O3, I was surprised at the poor signal, so instead of HSO I tried out Adam Block's HOO technique with S added in separately, but switching the O for S. Reasonably happy with the result, but it turned out a little cruncher than I'd like. I suppose astrophotography's just one lifelong learning exercise!
Usual RC plugins with PI and PS
https://www.astrobin.com/d65na9/