Do you have two ways of ducting out? I see “B” labeled twice If so, split the lights into two zones. Run the lights and ducts in a “s” like pattern drawing air though the one end of lights and exhausting out the other end
I'm a little confused as well. Are you going to be air cooling your lights is that why you have two exhaust fans? Or are you going to be pulling air from the actual room the lights are sitting in?
Yes I am!
So the problem with the way this is set up is you need to manifold the air properly. If it is all the same size the air is going to want to go through the easiest path and possibly not go through the other lighting.
Regardless of how you set it up, you can see if it is working properly by checking the temps of each string of lights and adjusting a damper on each run
I'll try to draw up a plan for you when I get home.
What size are the inline fans and how many CFM ? Maybe a link ?
What size are the holes on the ductable hoods?
What wattage are each hood? Link?
If the air coming inside is too cold I'd worry about moisture condensating.
Also you will most likely need more fans. To determine this you need to start with how many watts of lighting you are trying to cool in