Like many others I was a little frustrated with the reliability of my trackball. Even after cleaning it a couple of times. Instead of swapping the ball I decided to try to install a Glidepoint trackpad from Cirque (available through Mouser) that I had lying around. So far I am pretty happy with the result.
The trackpad is very low profile, the surface is still a little less than 1 mm below the top of the buttons. I will probably add a new cover that is going to increase the thicknes a little. The original cover the board came with got damaged when I desoldered the connector on the back but I have noticed that my finger does not slide quite as well on the bare PCB. I am also not sure about the look of the exposed silkscreen.
Very thin 30 AWG wires are routed through the hole for the trackball and another one I had to drill into the center frame of the uConsole right next to the display cable. The trackpad is then connected using I2C to an Adafruit QT Py RP2040. QMK supports the RP2040 and apparently also has some support for these trackpads but for now I am just using Circuitpython example code from 2bndy5 on Github.
I had to fiddle a little with the settings of the thing to deal with some yittering but it works pretty well now. The only issue is that it stops working completely if I do not touch the case of the uConsole 
Probably some EMI-issue since this does not happen when I connect the trackpad to my PC and the uConsole stays off. Not really sure what I could do about this other than using thicker shielded cable.
