AutoDMG is good stuff. Not sure of the instructions you reference (adding packages?), but it's really as simple as dropping a given OS X build (DL'd from App Store or through Recovery), getting the updates and building. We're not adding any additional software, but that's an option as well before the build process. We are starting to use it with a basic first boot script (e.g. drop a quick image/first boot config, let them enroll, and hit them with policy from there). You might check out Rich Trouton's GitHub for MANY great script examples. I believe Steve Wood linked a cool first boot script here recently as well (thin imaging thread?).
It sounds like you are NetBooting and using Casper Imaging? Diskless NetBoot is working properly for you (allowing you to unmount/wipe target drive)? You should be able to test your AutoDMG build by just using Disk Utility against another partition on your test machine (rule the dmg out).
