wouldn't it be best to simply put a Latin ending on his *original* name?
(not on the name he coined for himself).
He didn't have a surname before his father coined a Latin one. There are
plenty of places in Europe where not everyone had a surname 200 years ago.
In the Arabic world, for example, most people still don't have surnames --
for example Saddam is his first given name, Hussein is his second given
name, I don't know if any more follow, and al-Tikriti is how the clan is
called because it lives in Tikrit.