Is there an easy way to provide static ip configuration to a headless machine using pxe installing, without rebuiding the .iso or .squashfs files for every configuration?

I've recently messed about with pxe booting the installer, and out of curiosity looked briefly at providing preseeding without rebuilding the .iso file. A little research tells me turnkey common and appliance spesific preseed files are overlaid into the filesystem during build; that would suggest it should be possible to download inithooks.conf or another .gz or .squashfs file and overlay this at some point during initrd/boot as well.

https://www.turnkeylinux.org/docs/inithooks mentions a "pre-deployment script" but I cannot find any refrences to it, and it may not apply to the live/iso images?

If I have inithooks.conf downloaded and overlaid on the root to /etc/inithooks.conf I get a preseeded live system running without a installer, when passing di-live noinithooks to the kernel.

If I add auto url=http....preseed.cfg nothing happens either.

Sneaking files into the root filesystem mounted by the initrd doesn't get copied to the final install as the files that get copied are taken fom a fresh mount of the squashfs. So downloading and overlaying /usr/lib/inithooks/firstboot.d/29preseed didn't do much.

If nothing else I'm learning all sorts of interesting things by digging around in this :)