1st...your scrubber what you want to do is build a box for your scrubber to fit in, run a duct out of your cab to the box.hook a duct to your scrubber and run it out of your box with a fan/blower sucking air out.that way you scrub 100% of the air in your chamber, make sure the box is sealed.

2nd your intake..will your chamber be able to get fresh air when the central air shuts off?
3rd you want to have a second fan/blower for your light.i would go with a 6"inch inline fan mounted out side your cab sucking air through your hood,also use 6" ducting(most hoods have 6" flanges).you want to run your duct back out of the cab so you do not suck out stinky air.
i use passive intakes in my chamber and just let the central ac cool the room so the light gets cool air and i get cool air into my passive intakes.
this works ok i am planning to get one of those portable ac's.that way i don't have to run central ac as much.but with current sety up i can keep my light 15 inches away from canopy