I will participate but never good in organizing them. Here some old leagues that you can still find in the forum using subject line search:

Double Impact - there are many of them over the years. I am not sure whether sbadranga is still around.

pokerguy (for sure is around) ran few smaller leagues over time.

GraysGhost (on and off these days) ran something called Squadron Campaign 7+ yrs ago. Idea is similar to yours.

Trident Cup was a WSIM tournament ran by pbass111 who has become one with the force few years ago.

BlueDragon started something called WS&IM 2011 Championship some time ago.
http://youplay.it/play/forum_showmessage.asp?msgid=102343 I think finding BlueDragon could be tough but Electro wants to talk to him if you manage to dig him up.