You need to create a personal firmware build with "custom files". You can add whatever files you want on top of the basic firmware to create a final firmware to be flashed.
Those custom files can be your config files that override the default Openwrt ones.
I am doing that for my own build.
If identical settings for each router are ok for you, then that should be enough. The router might work right out of the flash.
(You can set wireless options for many routers so that you can avoid giving exact hardware MAC addresses in config.)
If you need different settings for site A and site B, create a directory where you store the settings as Openwrt settings backups. They can then be restored via Luci GUI.
(You configure one router for site A, and "backup" its settings via Luci GUI to create the settings archive file, e.g. /etc/Settings_for_company_X/Site_A.tar.gz. Then the same for site B. So that all optional settings are stored in the same directory in the firmware and the low-level tech can select the correct archive to restore.)
(Last edited by hnyman on 28 Jul 2014, 19:24)