For the common base image, I just build a normal Debian image, customize it (chroot) and flash it directly. For customization, maintenance and operations you want some sort of CM (Ansible, Salt, Chef or Puppet). There is also Packer, but it's not that easy to use for bare-metal images for some reason.

You could also do something like userdata where you have a script or playbook that runs on first boot and performs additional setup.

I've been meaning to try out PXE booting but am yet to.