Light trap and ventilation

Hi
I've picked up an old kitchen unit I'm planning to covert to a grow box. Its 1.5m tall, 600mm wide and 750mm deep. It has a divider that is fixed so I have one space 500mm tall and one 1metre tall. Any ideas on how to ventilate both boxes with one fan. I'm thinking of drilling holes in base at the back in the floor, then thru divider in same place. If I add another shelf 50mm up with ventilation holes drilled at front this will eliminate light from top box. Then exhaust thru rear of top box thru the top of it. In effect drawing the air thru in a "S" shape. Does this sound like it will work? Any tips appreciated. Also how many plants would you grow in this size box. Ill be running clf's for a start. How many watts per box is ideal? Small box for veg, large box for flower. Cheers

Take the back off the unit, set a new back into the unit allowing room for duct and a fan, run a Y slitter from the fan to two lengths of duct and for each cut a hole in the new back of the unit, one for each compartment. Use roughly the same length of duct for each so its even and the same size filter if your going to use one (4" is the smallest you can get)
The filter will help with stopping light going from one area to the other.

Buy some aluminium foil tape which is strong and light proof and line all internal edges to make sure no gaps.
Also cut an extra hole low in each cab to allow passive intake. You should have space for a light trap in the back.

Its tricky using small space. But you could fit 4 small plants or 1 medium plant in flower.

Cheers, makes more sense.