It seems like the max_payout would work, but it wouldn't and here's why:
Users would be able to post to our Community & DAPP from 3rd party front-ends like Hive.Blog and @peakd with those Posts (Buzz's) being exempted from the max_payout code that we hardcode into our DAPP.
Users would then be incentivised to post to our DAPP from 3rd party front-ends and our real users would be punished by being restricted by in-house rules that are not applied to Buzz's posted from 3rd party front-ends.
Please consider the above scenario and comment / share accordingly.