I have an issue with the idea of "passing." First of all, if you can "pass," then you're white. You're only not white if you, or others, subscribe to the " one-drop" rule.
That having been said, I'm not aware of Meghan Markle deliberately attempting to "pass" for white. Pictures of her as a teen, when she already had a public presence, show a little butter-scotch-colored girl with very curly ringlets. Not to mention, people who attempt to "pass" don't travel with their identifiably black mothers. While she may have had "light-skin privilege," even light-skinned people of color suffer from racial prejudice. Neither she, nor we, anticipated that the full weight of British racism would be used to crush her. I hope that she and Harry have a lot of love and strength.