Blonde remains to be the most coveted hair colours in the beauty world.
I understand your internal conflict completely and my heart goes out to you. Mormonism is a lot more controlling and has a lot more downsides.
You need to do this ceremony first where you end up pledging all your money and property to the church: It's cruel to suggest it.
In the meantime, she will probably view you as being less than a Mormon man who is a faithful priesthood holder.
She's already past her prime in the Mormon dating market. But from what you said, this girl doesn't sound like she is going to be content to have a marriage for time only.