soft delete maintenance? (advice needed ASAP)

[Birched]

Is there a way to traverse the database and hard delete everything that's been soft deleted? (Ideally, after a time interval?)

I looked through the threads here and the maintenance scripts, and didn't see it. Did I miss something?

If this does *not* exist as a built-in function, is there a reason that I should not construct a mysql query to remove soft-deleted threads from the database? And if I did do that, what further steps would I have to take to ensure continued happiness of the database? (perhaps rebuild threads? anything else?)

Thanks!