Question: How to change *.conf and rebuild kali?

Hi folks,

maybe I missed something, but I still found no solution for my problem.

I want to build kali, but with some own configurations. Exactly I want to use my own
/usr/share/X11/xorg.conf.d/50-synaptics.conf.

For rebuilds I could also add ~/live-build-config/chroot/etc/X11/xorg.conf.d/50-synaptics.conf

But: I still found no way, to rebuild the image, once it is done. The only way is to use "lb clean --purge", but that deletes my chroot, of course.
I tried also "lb clean --binary", but then a "lb build" crashes because some directories are missing.

Is there any other way, to change a chroot and rebuild kali again?

It would also be a solution, if I could just create the filesystem.squashfs after my changes. In my case I am using a sd-card, where I installed the binary.hybrid.iso with xboot. Xboot is a multiboot installer. Doing so, I am able to get access to the filesystem.squashfs on the sd-card and can exchange it. This works!

For the interesting: If There is a solution for my problem, this creates the interesting opportunity to chroot into the chroot, doing all your special needs like in a normal system and get finally a complete preconfigured Livefile system.

Thank you very much for any help!

Best regards

Hans