There’s no correct answer for this question. I agree with the half/full day rates, but in this scenario, charging hourly works just fine. Charge whatever you feel your time is worth. If they balk, see if you can negotiate. You can base it on what others charge if you want, but that’s how much they think they are worth, not what you think you are worth.
When I was in college I would charge $80/hour for one camera on a tripod. This didn’t include any editing. Maybe start at $120 and if they seem hesitant, offer them an “exclusive” discount of 10% because…insert reason here…They’re X type of company, You like his haircut, etc. People love feeling exclusive.
Good luck.