this guy got almost 13hrs on just wifi standby. Hopefully that would be enough.
You miiight be able to extend the time if you turn the LEDs off. I doubt it would amount to much savings though.
I wonder if there's a difference in battery life when using the remote vs the smartphone app. The smartphone app gets the preview which I imagine would take extra battery life. I wonder if that's still sent if you're connected via the remote.