Well, I'm somewhat of an expert myself, but I think you're right. The most logical way to do it is to close the board. I *could* edit the import script or write my own to import everything past a certain timestamp, but why bother?
Just means I'll have to drop and recreate the db when I ready to go live and rerun everything, but first I'll have to announce the downtime and prepare everyone for it. I'll play around with the present setup to discover any other gotchas and prep the owners for the inevitable downtime.
Thanks for the input.