Yeah, Rping when other people are just trying to talk can be inconsiderate, but feel free to do it if its only you (the RPers) who are around or youve asked anyone else on the server and they say its okay.
Moreover, I could install a plugin that could give us a separate RP chat. It wouldnt be too hard to implement, but I'd only want to put it in if there are people who would frequently use it.