Here is a pic of the backside, with the wiring / mounting.
I modified the included power cable to power both panels and the i75, and have a plug to plug into the power supply. I used this as the plug for the power supply.
T Connector Male-Female Pair (pimoroni.com)
5V 4A switching power supply.
The front side looks like this. The colors washed out trying to get the detail so I fiddled around and took two pics.
Too prevent power issues from two +5V sources, I modified a USB cable so its Data only. The +5V wire was cut. Everything has the one common ground, and the display / i75 is all powered by the one dedicated power supply.