I've been looking into getting a 12 volt heating/AC unit (normally for an RV) that goes over hatches and it occurred to me that the space under the air scoops on the deck (replacing them) might be the best place rather than over a hatch. As well there is already a bar there to protect it. My question is this... what is between the deck and the interior ceiling. It seems to be about 4" of dead space

