In my experience people think it's a length of boot/toe issue but it may not be, it could be a slight height issue in the toebox.
I've had a hard time explaining it but here goes. Sitting there in your bare feet, squeeze your big toe down on the nail using your fingers like a vice grip. Squeeze REALLY hard. If that pain roughly feels equivalent to what you feel when you bang your toes, then it may be height issue in the toebox.
If that's what it is, then all the filling and trimming may help a tiny bit but doesn't really help. If that's how you feel consider describing that to a bootfitter.
Most boot fitters can scrape/carve a bit of plastic to give you a little more height. That usually does it for me. I describe it as "please ream out top of toe box on big toe only to add a little more height up"