Not sure how much of a hassle it would be exactly, coming from my time with countless other forums and sites. As long as you have to have a registered account to post in it, shouldn't be too bad. Though it would prob be a good idea to get some really active vets such as stevie or smackutwice just to name a few to help monitor it.
SHOULD, emphasis on should as I'm not 100% sure how smf works, but they should be able to put a limit on posts per x amount of time. Could also possibly set it to having to be say, 100 posts or more to see the box or something.
There'd have to be some sort of rules and coding set in place to avoid spam, but it should be possible.