You can clone with
HTTPS or Subversion.
While having two usb drives (and providing the correct one to the platform-upgrade script), mount seems to fail:
Checking current boot device... detected c0t0d0 c1t0d0
Error: more than one removable device detected.
# ./platform-upgrade c0t0d0
Checking current boot device... using c0t0d0mount: No such file or directory
, mount failed
Yeah... That's not entirely intuitive. You need the full path. platform-upgrade /dev/rdsk/c0t0d0p1