Hello,
I'm very experienced with Debian administration and task automation; so I can help you to reach your purpose. Maybe clonezilla is a little bit overkill for a so restricted task: it can be done by including partimage and a custom shell script in the initramfs, and a custom boot option ("restore") may be used to trigger the script. That said, if you prefer to do it from a running clonezilla, this can be done this way too. Feel free to contact me for details.
Cheers,
martale