I use a Mindshift Backlight 26lt as it opens the way I like - the opening for the camera and lens compartment is against your back and when you swing it off your back and onto the ground/table/bench, the opening is facing you. Not only that, but you can swing it around your waist without the need to remove it and put it down and access your gear whilst the waist belt is still attached.
Here is the Z9 + 24-70 f2.8S, 14-24 f2.8S, 70-200 VR S, 500- f5.6 PF with FTZ attached (same size as the 600 PF and the 50 f1.2. You could swap out the 50 f1.2 and put in another Z8. My spare batteries go in the bottom left (there are caps in this photo) and I put filters or other small odds and end in the top left spot. Plenty of expansion in the large pockets on the back of the bag for coats, cleaning gear and a pocket for a Pad or Laptop. This is a great bag for what you would require. I have two of them as well as the 18L I took to Vietnam and Cambodia and the 36LT for my 800 PF and other lenses.