I like the idea a lot, but it wouldn't exactly be easy. To make it work right, you'd have to match the right surnames with the right family names, AND match the name with the type of unit.
For instance, it would make absolutly no sense for a Sea Raider to have a name like "Roger Bywater" -but that name would *work* for a mercinary in Zendar, or maybe a swabian. "Drogo son of Benta" is a name that obviously corresponds to the Khergit raiders, Ulfmaki Hrolfson is Sea Raider (maybe Vaeger) and someone with a name like Nikoli Renduski would need to be Vaegir.
Even more than that, you can't have a peasant with a Noble's name! You can't let someone named Bertrand or Godfreid or Roland be a peasant, nor can you let a Wat, Rickon or Cath be noble.
So yes, I love the idea. But it would take a lot of work.