Those sort of hoods are commonly used for marine setups. A point to consider is condensation. It is best to use a glass lid on the tank, even with a hood like that, and then make sure you design a drip plate if the tank does not already have one. course then you lose some of the light as it reflects off the glass, and passes through it, and then the water. With a tank that high, I do not think you can afford to lose any more light. For the display to look right, you will need the tank to be brighter than its surroundings, and that will be hard to achieve if you don't get lights that are powerful enough.
if the tank is dimmer than the surrounding there is no point lighting the tanks. That is why ALL fish shops have the aquatic section dimly lit with the tanks well lit.