This post suggests that we only need to create an executable script called /usr/sbin/policy-rc.d with only one command in it:
That should stop apt from trying to stop, start, or restart daemons when installing them in the chroot. That will probably keep the phone from rebooting, and will get rid of the need to hack the .postinst scripts.

But I agree that 4+ hours of installing the binaries and apps packages is a big job, and I wish I could post the finished image on my site...