A number of driver-related system files are difficult, if not impossible, to reconstruct. Files such as /etc/name_to_major, /etc/driver_aliases, /etc/driver_classes, and /etc/minor_perm can be corrupted if the driver crashes the system during installation. See the add_drv(1M) man page.
To be safe, make a backup copy of the root file system after the test machine is in the proper configuration. If you plan to modify the /etc/system file, make a backup copy of the file before making modifications.