You have one thread for all characters where everyone posts their various personas. If a new RP starts up, one can just link to their post in the stickied thread for their character information. Each RP can have two threads, one for the actual RP and the other for OOC posts, which would be the planning thread. They would be similarly named, ex. "Blah blah (RP)" and "Blah blah (OOC)". This is the way it's worked for various other RP forums on LF for a long time now.
have a suggestion for the lf poll? pm me