Oh just realized you said careful --cutting-- the filters. Won't need to do that thankfully; the window opening is about perfect for the sizes I'm dealing with.Just be careful cutting those filters! the fiberglass is really nasty on those..
I have a system adapted from the California Medicinal narcotic plant guys! I figured that they have battled harder than us in the KWh use, heat and filtration department.
So I went to my local (in SoCal) hydroponic store and asked a bunch of questions.
As far as your fans are concerned, I figure they are PWM but what is your projected kWh total vs. CFM
Also what size are the fans, type of static pressure do you think they produce?