I think some weird and creepy evidence is Red John's voice in the season 4 finale. Simon Baker's (patrick jane's) voice was obviously used !!!
https://www.youtube.com/watch?v=l_CK_90hei0   A simple pitch correction and you can hear simon baker.  
    I for one hope PJ is RJ.  Perhaps some disassociative personality disorder. What if the Red John persona is aware of the PJ persona...
anyway i hope patrick will have another mental break and realize he's rj. what better place for a child leaving the carnival than a pseudo religion like visualize and working on a farm.
but enough speculation.
    I'd like to hear others thoughts on simon baker's voice being used for RJ in the season 4 finale.