could you live in a box that is twice your width and and only as deep as you are wide?
you could but its not living.
as mentioned above a 55 is minimum.
Heh, I'm using a 55g as a grow-out tank for two GT's right now. I don't believe that a 55g is sufficient for full grown adult GT's.
There are plenty of other cichlids that are better off in a <55G tank. Anything that might look good on a dinner plate when full grown isn't going to be one of them.