Lack of interest forum - number of posts per month by User Group permissions

I'd like to have the ability to limit a forum to specified number of posts per month. It would be useful to have this by utilizing the User Group Permissions

For example;
  • I'd like to setup a "Limited Classifieds" forum where the Regular Registered members can post ads. But they would be limited to 1 thread per month in this forum
  • Then, I'd have another "Classifieds" forum where the Supporting Members can post ads with no time limits or increased limits