[Facts] Re: Maria as a male middle name
I'd be surprised to find it given to a non-Catholic boy. And using it as a mn makes a clear reference to the Virgin without giving the boy the life-long task of explaining that he really was a boy. I've seen several cases of French boys given a string of very Christian names, with hyphens: Jean-Paul-Marie for instance. No doubt this would be shortened for everyday use.
There was a case in 18th century England of a boy whose godmother was Queen Anne and who was given Anne as his first name. He was a member of the nobility and was, I think, Lord Anne Surname. But in those social circles, everyone would understand and respect his parents' choice - or his monarch's.