Echo - your dimensions reflect base, back, and hood. The tank dimensions are 16.9" L X 10.25 D X 8.75" H. With a couple inches of substrate, you are probably looking at 7" from lights to substrate.
If you do a search for fluval edge under the lighting section, you will find a huge number of threads on lighting solutions. Best of luck. I too am doing some investigation on a nice planted edge. IMHO, the tank esthetics more than make up for some of the limitations faced.
I'm struggling with additional lighting without impacting the edge's esthetics. That means adding something under the hood or perhaps a pendant above which doesn't impact viewing from above.
Best of luck,