How can I make a full, restorable image of my pre-root Android hard drive, as in Clonezilla?
In general, you need to root the device to make a full backup. After you've rooted the device, use nandroid (which it seems you already know about). You can make a backup that doesn't include the OS by following one of the answers to How do I perform a full pre-rooting backup of an Android phone?
By flashing the stock ROM and recovery for your device, and wiping the userdata partition. See Where can I find stock or custom ROMs for my Android device? to find the stock ROM for your phone.
Because if you've broken the OS, recovery, and bootloader on your device sufficiently that you can't just flash a ROM image the usual way, there's no way you'd be able to restore any kind of backup image.