I don't have any stacked tanks but I do have 2-125s 1-10 and 1-20L (soon) in a room thats about a 9' square and there is also a love seat in there too. It's the fishroom.
Basement Mostly Racked.... 180,300,135,90,90,75,75,55,29,29,29,20,20,10,10,10,10,10,10.. Thats all i have at the moment. Also have pond not running yet
Two 55s, one long one tall and two 20s a 10 and a 5 running along the windows of my living/dinning room, where my computer is.
Where is the dinning table? In the basement, under my dirty laundry and R/C airplane.
Because I am a grown up now and can do whatever I want!
Except afford to replace it all with just one big big tank.