Adding package to macOS Mojave USB Installer

Our organization uses clean installs of the latest MacOS every July.

Our previous solution was to remotely target a NetInstall startup disk which included a package. The package contained two apps a LaunchDaemon, and LaunchAgent. It creates the Administrator user, queries our directory for the hostname, prompts for hostname if device is not in the directory, then binds and enrolls the device on our servers, and sets some optimal system preferences.

With the deprecation of NetBoot, NetInstall, and NetRestore; we are resorting to physically accessing every device with a USB Installer. The Install macOS Mojave.app allows --install-package via the `startosinstall` comnand, but does not have a similar option for the `createinstallmedia` option.

Any suggestion that does not involve tools which are not native to macOS or macOS server?