Stick to what was agreed upon.
For a project like this, it would have been best for both parties to agree to one flat fee for the whole enchelada. This is the strength of the one man band today, being able to give this quotes.
That said, if you leave the house, it’s a half day. More than 5 hours is a full day. Don’t worry about the running time of the raw footage. Don’e even enter it into the equasion. Most of my ten hour shoots are less than 2 hours. It just takes that long for usable stuff to happen.
As for as post, they do realize the HUGE break you are giving them and will appriciate it. Surely no need to fret over their misaim on their script’s running time. Add nine minutes of a dancing bear if they are hell-bent on putting someone to sleep with their video. Shorter is better. The two of ya just celebrate and enjoy.
