txhandgunner wrote:
Maybe I just need some kind of booster in the ductwork towards the rear???
When I transit through the SW in the summer 3 ACs are needed/wanted. Many don't understand how hot that area can be in the summer. There are times when we don't have 50A and just run the rear AC. Your case may be different.
I planned to run some wiring in the PS vent and found out that it was completely blocked by the bathroom skylight. So check that yours are open.
Install some temporary muffin fans, close off some of the front ceiling vents and see what you get in the back.