Might I suggest a time limit for the games as well. Say, 2.5 hours each? Maybe a little less? I know at the last tournament I played it was 1500 points and we didn't have a whole lot of time, definately not more than 2 hours, but we still got most of the games done, or atleast into the final stages.
This way, with 20 tables, if you get 40 people playing(which is a BIG number) you can
wait..so, maybe a little less than 2 hours per game..