Just sharing an idea I had for a tall and narrow tank.
Using T5HO on both sides to give light to the bottom of the tank and a MH at the top.
The main issue I see is trying to clean the thing.
I seem to remember hearing that light coming from odd places (ie the sides of the tank rather than the top) is very confusing for the fish and throws them off..... but I'm not really sure.
I think the fact that the lights would 1.5' away from the corals and not having to have the light needing to pass threw the turbulent water on the surface makes having them on the side more of a plus than a negative.
This is really just something that came to me more than something I'm working on right now