[offsides]

That certainly seems like as good a system as any. I don't think there's any official "right" or "wrong" way to do it, as long as it's done in a fair and consistent manner. And that whatever method you use is explained to the participants before the tournament starts, so that there's no surprises down the line.

As I said, I like the whole random table assignments, but I'm guessing that as tournaments get bigger it becomes more unwieldy and makes less sense. Plus, I have occasionally had very poor mixing because of the way the dice fell, but that's the way it goes sometimes. As long as everyone has a good time, go for it :)