So, I decided to take a cheap 7" Amazon Fire tablet I got for $20 from a friend and mount it to the front of my printer! This way I could have the full Duet web interface.
I started by using the original 20x4 display mount and removing the display assembly from it. I took the back of the Fire tablet off, and put a few screws through it into the front of the old display mount. (the below picture is an earlier test fit, which is why the USB cable is still visible). The Fire tablet is really, really easy to take apart. You can get the back off by just running your fingernail around the edge.

I then decided I didn't want a USB cable hanging out the side. So I took the back off the tablet off again and found some conveniently labeled test points for the USB port. Soldered some wires on and ran them out a hole drilled in the back of the tablet case.

Crimped on a 2 pin locking connector and wired it to the +5V Standby power rail from my printer's ATX power supply. This way the tablet is always powered, even if the printer is off.

It works!

The final result

I am really happy with how it came out. I ended up using a kiosk browser app (https://play.google.com/store/apps/deta ... erov.fully). to get a full screen browser. Only setting I had to tweak was the "font size" setting in the browser app. Bumped to up to 140. This made the Duet web interface fit the tablet screen perfectly.