Hi,

First of all, I don't have any real theory that would confirm my accusation, I just hope it's him. I sort of like his character.

Furthermore if you read a crime novel (e.g Agatha Christie) you can come up with educated guesses but with The Mentalist it's different. To many suspects fit a part or all of the clues. 

I do believe that casting for Red John is trickier than we would think. Nobody can estimate in the first season precisely how long a show will go on so you always have to have character that could be RJ. If the show continues you can expand the legend and create new story lines. At least this is what I would do as a creator/executive producer and this is why we have so many possible suspects and theories.