forums and upgrades plugin integration with supporter

Hello - I did a search but couldn't see the answer. If you make forums an upgrades plugin (as you suggest), then you can only stop people making more forums. You can't make forums a supporter premium plugin at the same time because the forums plugin is in the upgrades folder.

Is there a way around this so that:
free users can make no forums
supporters can make 1 forum
more forums can be purchased as upgrades.

I've tried setting the forums config file , max forums to 0 which does prevent any forums but it still has the 'click here to add new forum' link which leads to an empty dashboard screen

Thanks for any help you can give.