I added a hardware section to the github where you can find the schematics.
If you are interested in bringing up an xmega project there is a lot of code in the firmware section you might want. Specifically the xmega_init, _eeprom, _interrupt and _rtc files are generally useful beyond just TinyG. Also, the Xmegas have issues with writing to non-volatile memory (Flash and EEPROM). If you intend to use these functions there is some very necessary code in the _eeprom file that implements the Atmel Errata instructions.
Also, the xio_ code implements a set of AVR GCC Stdio compatible device drivers for serial IO and memory-file IO.
– Alden