I really like the detail and colours in the nebulosity Colin.
As for the halos, what Rick suggested works very well for me, and I tend to have even bigger OIII halos with my doublet. I found that the key here is to create an adequate star mask that needs to be modified for SII and OIII to include larger areas, and then I use AWT twice or three times to remove the stars in order to create tone maps for RGB.
I have also found that instead of adding original SII and OIII, it works better to add SII and OIII tone masks (starless) to Ha to create enhanced Luminance.
In some extreme cases, you can use CloneStamp tool on the tone maps to get rid of halos...but please do not mention it out loud, such practices are forbidden
