Initial Setup Post-Install

Just wondering about what some folks have done to skip the process after an InstaDMG image is applied to a mac - after we apply the image and reboot the mac it still goes through its startup routine...asking for user info, timezone, registration, etc. Normally in the past I would just touch /var/db/.AppleSetupDone and set the rest of the items using a payload-free package. ...and make sure everything is set in the config files. I do this using a variety of methods...creating payload-free packages and dropping them into the custom packages component of InstaDMG would appear to be the most logical..but nothing appears to be working. Am I missing something? Thanks, j