First thanks for the site and the work it entails.
I am not opposed to the concept but I am worried about the admin work to support. The mods are volunteers (I believe) and this could create an overload for them to manage.
Whatever direction you head, I suggest it be a light touch but if you need to warn make it a heavy penalty. If someone crosses the well defined line then penalize with a suspension with a defined time out. If they are repeat offenders, ban them. So, make the offenses fewer but react quicker/with more severe consequences.
This board is not a right but a privilege and those here should treat it as such.