I think you’re all onto something here, we just need to shape it into something coherent.
Judging by all of my previous experiences with different MMOs and other games, people come on forums for a number of reasons (information, jokes, RP, social media, video sharing, etc). We would be wrong to force anyone into the RP section; the people who want to participate, will do so.
Therefore, I think that we can create a set of rules (or use an existing set) to use in the RP subforum. One of the rules can even state that a person can post in there only after being approved by the GM, which can happen after the person has been with us for a shift or two, since that’s how long it takes to start grasping the canon.
We would all love to have many more people RP in here, but I don’t think that a few rules is something that would stop a person who wants to RP; rather, I think it might be too daunting to hop in without the rules, since one doesn’t know what’s expected of him. I’ve missed out on few forum RP games because I didn’t know what was allowed, and what was shunned, and there was no point in reading over a hundred pages to see what I can conclude what the rules are. If we’re talking about motivating others to RP with us, I think the best motivation would be having interesting stories happening during the week.