I saw this theory off of Tumblr or something, but the evidence there is pretty solid! In fact, it's very solid!
Does that look familiar? Let's see...
"IDENTITY NOT YET RELEASED DUE TO HIS PUBLIC PERSONA"
From here we already know it's a male. Also, being a famous mascot is pretty much a good reason for a secret identity -- believe me, it happened before. (Aunt Arctic, anyone?)
"KNOWN ASSOCIATES: All EPF Agents and island musicians."
Huge hint, right there. Franky is friends with G Billy, Petey K, Stompin' Bob and Cadence -- they are all island musicians. As well as that, the tic-tac-toe code on the bottom reads "ROCK ON". Very inconspicuous.
So, what do you think? Usually I don't like the idea of a newbie joining a well-established group, but I'm excited for this!