Note that config files will be saved in sysupgrade.
You should only need to install the packages.
As you have only a few packages, it is pretty straightforward to write a shell script like:
opkg update
opkg install luci-app-wol
opkg install dns-scripts_no-ip_com
opkg install luci-app-ddns
opkg install luci-app-openvpn
opkg install luci-app-wifischedule
opkg install luci-app-sqm
And if store that is a subdirectory in /etc/config, it should get included in the sysupgrade backup.