There is actually an MSI parameter to pre-define the UUID of an agent when it is being installed (P_CMD_PRODUCT_GUID=""). You could have a simple startup-script to generate a hash of the machine-name, format it into the GUID the ERA/Agent expects it to be, and pass it on during installation.
You could add this script to the startup procedure of your actual machines (Not Golden Master/Image!) so that when the machine is booted from the GM, the agent is installed using a UUID based on the machine name.