Not a theory, but surely Rosalind Harker must be lying about the physical description? If not, then wouldn't have RJ killed her already? He normally kills his minions when they're no longer needed, yet she's still alive, which suggests to me that she still has a purpose, and that is to throw off any potential invstigators by purposely giving false info.

On that logic, working to the opposites of the given description, RJ must either be:

Very tall or rather short
Muscular or fat
Bald or have longer/curly hair

Only one man really fits all 3 points: Gale Bertram (tall, well built, bald(ing)), but he would be too obvious, and this show doesn't like obvious suspects. 

Reede Smith is chubby, so he could be considered, plus he's confirmed to appear in episode 6:08 (Red John), as well as 6:02 (Black winged Redbird).

Also, i'm unsure as to how genuine the suspect list is. I know Bruno Heller has said it is legit, but Bruno Heller also said that the guy in 3:24 was RJ, and we know how that turned out. Wouldn't surprise me if he was lying to protect the script.