Ha-ha Stein, you did it again =p
I have been pondering this as well as many other things, I was thinking 3d print a controller similar to one of the common game controllers and just add two of the joysticks on the bottom and shorten them up so its almost flat, it would take a bit of getting used to but you would be able to control everything at the same time.
There's also a track pad controller that's very adaptable and has a ton of options and buttons from steam. it hooks up via Bluetooth to computers and steam link
https://www.amazon.com/gp/aw/d/B016K...TwL&ref=plSrch