Skull plate isn't wide enough. What can I do?

The form for my pronghorn just came in but it seems like the skull piece doesn't fit the way it needs to. I don't think it's wide enough. So I wanted to ask what the best way to work around this would be? Ik that there are fake skull plates that you can use when the original skull is broken but sadly the one I found is unavailable. Is there any way that I can still use my own skull?

Also this isn't as important of a question but why isn't the eye socket on the form hollow?