That looks pretty good! It would necessitate a redesign of the center console for the ducts.
My 05 Tahoe I had used vents in the ceiling and had a controller overhead for that zone of the AC and should have been implemented in the K2 trucks similarly. But, the cab volume is not that of an SUV, so if you run your fans at full speed and set it to blow from the floor vents and the forward vents, you enhance the cooling in the rear. But I've found that just blasting the front vents cools the whole truck pretty fast.
Remote start before you get in via the Onstar app and by the time you get in, the entire interior is damn near 60 degrees.