Thanks for this guide !
There's simple way to store changes in dnsmasq.conf.
According to one of Oleg's posts /etc/dnsmasq.conf generates at every boot. To make any permanent changes you must create /usr/local/etc/dnsmasq.conf file, edit it as you wish and flashfs it. After that system will generate /etc/dnsmasq.conf as usual at every boot, but any lines stored in /usr/local/etc/dnsmasq.conf will be automatically appended to /etc/dnsmasq.conf