Nan, please reconsider your advice before you condemn this young man to a lifetime of bad Gary Coleman impersonations!
Surely there are enough variants of William that he could accomplish this without a name change (not that I'm opposed to such).
In 50 years, will there be ANY guy names left, or will they all have been co-opted by the "creative" parents of females? For instance, how did "Hunter" get to be a girl's name? Shouldn't that have been "Gatherer"?
The Canadians have a simpler solution to girl's names. If they can both sing and yodel, they're named "Sarah". Otherwise, they're named "Fiona" and given Highland dance lessons.
My roommate in college had two "Sloan" middle names plus a Roman numeral. He married money and became a sleazy lawyer (even for a lawyer). Nuff said.