Getting ready to start a sog myself… nothing this ambitious, just some strain testing/hunting. Prolly more like 14-18 girls in a 2.5x4.5. I found these 2 gallon bags that are really cool. Only 7 inches diameter, but just over 12 inches high. Should be able to stack them in nice and tight and still give the ladies 2 gallons of coco to push with. They are for propagating tree cuttings, but should work great for a project like this. They are just over a buck apiece. Pretty sure they came from 247garden. Incidentally, hat tip to the dedication that this project has required. The world needs more people who are willing to try shit instead of just listening to the last guy. Cheers