For those searching a fully packed firmware image, based on the @robimarko IPQ807X code, with the all specific packages you would need, check this topic: IPQ807x OpenWrt Sysupgrade Server
Straight from the LuCI webpage, using the luci-app-attendedsysupgrade package (also known as Attended Sysupgrade). No need to compile firmware or packages by yourself.
@robimarko would you put this info in the first post?