That's coming along rather well now Funnily enough adding Ha might bring out more of the red/pink you were looking for!
I usually apply background correction to the individual channels before combining - my reasoning is that light pollution/moonlight etc gradients will change over the night so RGB and L can all have quite different backgrounds to remove. The more complicated the background gradient the harder it is to model and remove, so I think it makes sense to try and tackle the individual channels rather than trying to model the whole thing at once. You can always run ABE or DBE again on the color composite to clean up any residual colour gradients.
You probably already know about them, but when I started with Pixinsight I found the tutorials at https://www.lightvortexastronomy.com/tutorials.html very helpful.