Sub away.
But if I were you everything I made for him I'd use his email and name since they will be his sites and if someday he decides to make them himself he won't need to change anything. That's assuming he will be hosting his own domains and sites? Another reason of being if he changed anything it wouldn't/shoudn't effect your own listings.
Also Link-O-Rama and a few others won't allow it. Some scripts detect various settings to not allow more than one submit per day.