Chris-both units are separate. The rear unit feeds the dinette area (which can blow to the front-I anticipate using this unit for night time use) and has a T to feed the bedroom. They have individual vents that can be shut off. The 8" return is under the dinette with a 12" square filter vent. The front feeds just one vent-I wanted that one to blow hard if need be. The return is built into the end table of the sofa also with a 12" filter vent.
In the basement (which is part of the interior of the box) is two luovered exterior doors that the A/C units are mounted just inside. The 6" hot exhaust from the condenser will be ducted under the truck. Since the floor of the box is 42" up from the ground, I don't anticipate any problems with heat. So the condenser air is drawn in from the side and exhausts underneath-very hard to have the two mix. Good Luck, TomC
