Greetings @dleberfinger,
When it comes to most customization the recommended process is with our TorizonCore Builder tool as shown here: Capturing Changes in the Configuration of a Board on Torizon OS | Toradex Developer Center
That said, /etc/hostname is a bit of a special case since it can’t be customized by TorizonCore Builder. What could be done instead is creating a script that runs on boot that will customize the hostname on your device. You can then use TorizonCore Builder to capture this script and service and create a custom image that can then be deployed to multiple devices.
This idea is described in another thread here: Image customization and folders
Would something like this be sufficient for your needs?
Best Regards,
Jeremias