Light doesn't need to know his victim's real name. He can easily find out a way to discover PW's real name, kill him, and then finish everyone else off while giving PW only enough time to yell "OBJECTION!". Besides, PW has declared, open, straight-out friends, while Light has a wide variety of unknown tools, manipulating them from under the shadows. So yeah, Light would win by a mile, although I hate the idiot with a red hot passion.
Oh, btw, nice idea.