I tried copying and renaming that character file but all that did was create a copy of the character with the same name. It might be possible with the right program to edit the character file though. Otherwise hopefully something the devs will implement in the future, along with the ability to change appearance.

In the meantime you could always make a fresh character with the name you want and just outfit them with all your old character's gear. would still have to relevel skills and probably unlock crafting recipes again though.