Re: Ben Harden Method / Modified
I think the essence of the Ben Harden method is to use the blanks for the purpose of crowding the bees more. However if you are going to use a 3 brood box hive & just put blanks in one box, it may not have the intended effect.
Really, the Ben Harden method is just a simplified version of the method used by many commercial queen breeders, but a few steps are removed, such as using really strong hives but instead cramming the bees by using blanks. What I think you should do, is in your 3 brood box hive, if you find all the brood combs can be crammed into 2 boxes, temporarily do that, then go ahead with the Ben Harden method. But if the hive is so strong you cannot do that, then go ahead as you suggested.
My opinion only, and it's likely others will have good, or better, ideas. I've not seen the hive.
"Thinking Inside The Box"