I believe that there should be a party plugin for creative that can have its own private chat for the party. This means that when role plays are going on they can just talk in party chat. This will majorly get rid of alot of the the spam in chat. plugin: http://www.curse.com/bukkit-plugins/minecraft/partymanager
Support! The chat will still be filled up with messages like - TP to me for an OP shop. Tpa for an epic head shop! RP, just tp to me! On the other hand though, at least the chat won't be filled with "actors".
This could be a trouble to moderate all sexual RP parties, and player reports would be cut down severely since outsiders cannot see, giving people the opportunity to violate rules, plot evil towards the server, and just be jerks all-around, walking away unscathed. While RP chats are annoying in public, it'd be far better for keeping the server safe then isolating multiple chats to consistently check all the time.