Keep Internal Drive Segments Unmounted While Booting from External Device

For forensic imaging of drives and/or segments with a native Mac application, I'm booting from external device (usb, hdd, etc.) into BaseSystem. I want to keep the internal drives and/or segments unmounted during the boot process. Later will disable disk arbitration, mount these drives/segments and image them. Since the drives should be kept unmounted, there is no way of knowing drive/segment volume names and/or UUID.

I've created a deamon (System/Library/LaunchDeamons) for mount blocking (on external boot device), but it only blocks newly attached devices, not internal ones.

Also, I've also tried disabling "diskarbitrationd" daemon (desperately, on external boot device), but not worked.

Note: I've created boot image from BaseSystem.dmg of Sierra (10.12.1), and modified the contents.