Sounds like one key is to use plastic tubs to be able to slide things around. I now have the door dimensions on my phone so I will have to shop for the optimal/max size.
I have contemplated the pole with hook.
Storage access from above is an interesting idea. I had contemplated installing a tip out door/drawer on the side away from the closet to serve as a dirty clothes hamper. I have also looked at that space to hold one of the built-in vacuum systems.
I hear all of you on the flimsy panel separating the two sides of the compartment. I have already done the 1/2" plywood panel replacement. In the process I moved the water pump and the panel over 6-12" towards the DS making the basic compartment even larger. This is what I did with the panel:
It now has my main power distribution on it with solar controller, 40A Maxi fuse for house power, spare Maxi fuse for potential future inverter, 6 fuse block for slides/etc, current measurement shunt, and the front slide controller. No more breaker/fuses on the frame
For storage cleanup I just finished doing a peg board panel across the front: