The big difference, though, is that my tank has an all glass top without any of the plastic in the back that Grizzarian's photo shows. Is the plastic removable? I wouldn't think it would be bracing. If it doesn't come out more than 10" from the corner, then the corner tank layout in the link could work for you anyway.
I don't claim to know much about leds, but there are par38 lamps that might work well with the circle. I don't know about light spread, though, but that might be the best option if the plastic comes out too far. I'm not confident 2 cfls would do it for you.