After spending the past month on optimizing the design for the Steam Deck and using this as my daily driver, I have a few observations:
1. Not all the computers I use have a high bandwidth USB-C port, so direct access to the keyboard USB plug is necessary. 

     Perhaps an external patch cable would be sexy and practical?

2. Clean lines on the surface of the chassis are really important to me. It's sort of the opposite of 'modular' but seeing and feeling those seams drives me nuts.

      I can create the appearance of a solid shell by covering the split in the left and right halves with a panel cover. I think it would work well, especially if I use an accent color. I'm thinking about design cues pulled from Tron Legacy + Deathloop. A retrofuturistic accent, with smoothly curved hexagons.

3. The hinge is feeling less important. I think I can do a good job with a notch (like the Lenovo book 9i), as long as I have a way to hold the device in place while using it in the lap.

4. My obsession with keeping the chassis depth down is holding me back. The right side battery module looks great and works great as a handle, but it takes up too much space on the desk.

     I think the original design with the battery on the left, pointing backwards, and the dock in the rear is more practical, even though it adds depth to the chassis.

5. It's time in increase the height of the chassis by maybe 4 mm. 

     a. I need a couple more mm to cleanly mount the 4 port USB hub, without cracking it out of its shell.

     b. If I had a couple more mm in height, all the keys could rest lower than the chassis, so I could make a nice cover for it.

     c. If I had a few more mm height, I could add support for more USB-C NVME kits. I have a good one, and I don't really want to spend $25 buying a new one just because it's 2mm smaller.

I'm going to move forward with the following design: Slim with the Deck Dock on the Left, Modular USB Hub and Battery components, Nook instead of Hinge.

Once I have the designs for that finalized, I'll make a version that is not modular (except for the battery), and see how that feels.

Then I'll turn my focus on a more universal design, using a different dock, mounted in the rear.