urbanbe, I have also been looking for an answer to this question. The best answer that I have found is to have a bar of honey for each bar of clustered bees. I haven't found a minimum hive size, but one of my books says at least 12 bars (a New Mexico author). I have 2 first year top bar hives, one with 24 drawn bars and one with about 20. I also have a warre hive with one box full, they don't seem to want to move to the second box.
Oblio13, I am curious why your hives haven't made it in the past. I have a top bar hive in southern NH, and am trying to figure out what the major obstacles are In this area. Do you think they aren't making it because of condensation, starving, freezing, or something else?