Hello @Steven65
If someone wanted to use my listing for commercial purposes, then I would be looking to charge them a commercial rate and would want them to show me they had appropriate liability insurance and have a separate contract to indicate how it was being used, how many people were using the property etc.
I certainly wouldn't be letting them stay at Airbnb rates.
I would also confirm that I wouldn't be able to provide access prior to booking, but may alllow them to come and visit prior to the shoot, once they had booked, if it was convenient.
Having a photo of a guest won't help to show they are genuine I'm afraid.
In your situation, I would withdraw the pre-approval and let the guest know if they want to book for a photo shoot you would need to discuss terms, see their liability insurance and agree a commercial rate.