I'll be watching this space with interest, Vonnie. I'm a New Zealander of Scottish and English descent; my husband is Maori, which were the people living here before the Colonials arrived and pinched all the best land! Certainly, here, there are plenty of mixed race marriages.
My latest novel has a mixed race relationship in it, and I confess, I hadn't thought much about the wider implications of that. I don't think it will hurt sales here in NZ (I'm being very positive here, and assuming my publisher is going to love it

) but overseas - who knows.
I don't have any American publishing experience so won't give advise, but I will be looking in on this post.
PS. Follow your heart, write what you have to write, let the story lead you where it wants. (But that isn't advise!)