I noticed in the pics I've seen of the AC systems (Danhard,Starcool) that there are only vents for the lower part of the van,but the penthouse has none. Please correct me if I 'm wrong. Couldn 't a small cut out be made in the bed and a vent be sent to the PH?
Notice that the vents are near top of cabinets.Could a vent be added on top corresponding to a cutout in the bed with an optional snorkel to get the coolness up near the penthouse roof?
behind the back roof latch would be the best option, IMHO, you don't want to cut or get into the sides, but the back flat part is largely empty/¼ ply and easy to remove the upholstery to investigate and plan a route that misses wires and frame pieces.