I think Bertram is Red John and that PJ was close to catching him a couple of seasons ago in the mall but RJ was one step ahead of him with the fake RJ. This was a plan to get PJ locked up for a while as he was close. 

Bertram could easily bug the CBI office and be a step ahead at all times, it's only patrick that doesn't give his plans away and that's the only way he can get close.

The tyger tyger 3 all meet in Bertrams office, which to me signals he's the more powerful of the 3 remaining suspects. 

There are many of your theories that make me think it could be any of the suspects, and the last episode with Stiles essentially baptising two women with blood using the same 3 fingers RJ uses to paint his smiley face is a bit baffling. He obviously has something to do with RJ.