That's not going to work good. That's going to work great! I like it. Nice!
I'm Stoked on how everything is coming together! Going to put a nice fan on the light and filter, about 500cfm, and use a gable vent or inline, 500cfm minimum, for emergency exhaust on a thermistor.
Everything will have semi ridged duct work.
6"x24" carbon filter to a 5" semi ridged duct, then to the light and out the opposite side of the hood stepped up to 6" semi ridged duct to the fan and out the ceiling into the attic.
Attic will be vented with exhaust fans on the turbine stacks eventually for overall efficiency on the home A/C.
The light hood will be like a jet engine diffuser. letting the air expand, witch helps cooling and the preceding 5" duct from the filter will create a higher velocity and lower pressure (Bernoulli principal) on entry creating a ram air effect entry and a vacuum out the 6" at the convergence on the exhaust. ....HOPEFULLY. LOL!