Thickness of the XCAP is 3.62mm

Yes, it is boring and tedious but to ensure that this guide compares like to like it is felt to be necessary.

For the question on Answers, the batteries were all charged using a “Fast Charging Activation Test Fixture” by Jageud.During those tests the board only managed to charge all three batteries to around 4.09Volt.

I did not want to use my lab power supply but wanted to stay with equipment that others may have available as well. As a tinkerer by heart, I opted for an Apple charger as well as an Apple charge cable. I hacked the original 30 pin connector off and determine + and - wires

I then connected the positive to positive and negative to negative directly to the prototype board, bypassing any communication etc. from the battery to the charger. Charging was monitored with a USB ammeter. All batteries were charged this way to around 4.24V. It is possible that this is where the battery protection prevents overcharging.