It seems to me that the problem with a 6' tank is the bowing horizontally, not vertically. What if you did it in even more than three panels? What about doing 4-6 panels? A panel only a 1' to 1.5' wide shouldn't bow. You could even make a series of doors, i.e. if you made it a 6 panel construction, you could have the panel one door open to the right, the panel 2 door open to the left, 3 to the right, etc., etc., etc. That would also give you the freedom to feed whereever you like, and (more importantly) take lots of top down photos.
