You've definitely got better data there than your current processed image shows.
I grabbed your fits file and had a quick play:
I opened it in DSS and saved out a 16 bit TIFF. From there I used PS to muck around. Since it was quick: auto tone, auto colour, auto contrast, manually adjusted levels, brightness and contrast, ran the HLVG plugin (removes a lot of green), little bit of vibrance/saturation, and "small" sharpness filter.
I think it's possible to do way better given time, effort, etc.
Good thing is you can always reprocess these things - I should know since I often end up with multiple versions.