This has been tried many, many times on the more dedicated RCT forums; mainly Atari.
It almost always doesn't work for different reasons.
That said, it has worked a few times. It might be better here since people know each other better what with meets etc happening on a regular basis. People will be more committed and less likely to flake. The only times it has worked on other sites is when it has been a competition and involved teams competing. The drive to actually get started doesn't seem to materialise when there isn't a deadline or specific goals.
I have tried this before and it hasn't worked out so I'm not really interested. Good luck though!
I have set up a ballot box thread (head over there to see what I mean) so that we can make sure this is properly organised like you said, because it'd be a shame if it diddnt happen!