I would reconsider pulling air from inside a bay, You will be pulling dirty, odors and all kinds of creepy stuff in through air leaks
in the plumbing and electrical tunnel. Have you looked in there at the coat of SOOT? It gets sucked from the engine bay
all the way up into the stock a/c air intake if any of the rubber seals are missing.
Also if you have any pass through holes between the bays you may also be pulling a negative pressure in them as well and
there is a lot of stinky stuff down there that honestly you wouldn't be happy about smelling.
Oh, Well... My 2 cents worth.. Cause I been there a few times...