Borax or salt??

I have a nice bird skin I bought that has quite a bit of fat still lingering that I am having trouble scraping without damaging the skin. I tried Borax but it doesn't seem to help much. Would salt work better or is there another trick I should try?

By the way most of the fat is in the vicinity of the wing joints. Would removing the wings help?

Thanks in advance for any help you can offer!