I have a a meaty instep. I have normal arches, but a high instep. If I try to buckle the lower buckles on my boots (even at the loosest setting), the pressure causes the outside of foot to feel crushed. I always end up skiing with the two bottom buckles undone. Even then I sometimes get the pain, but not enough or to a level that I've decided to do anything about it. I have had this problem with every boot I buy.
I have a pair of X Wave 9's with custom footbeds. Fit is otherwise pretty good. My feet are otherwise average width throughout, although I do usually need something with a tight ankle pocket to keep my heel
I've moved since purchasing boots, otherwise I would go back to where I bought them to see what could be done.
a) have my existing boots worked on? Does grinding the bootboard down help?
b) consider new boots. Is there something that offers more room over the instep without providing too much arch support?