I just saw the portfolio on your website and I must compliment you for making awesome pictures.By the 1:1 rule you should only 5m from people when ≤5m AGL. It is a lot easier to gauge distances when the drone is so low. Still, I probably wouldn't be able to tell between 4m and 5m. But I could probably tell between 3m and 5m.
Of course, as you say, after the fact it would be very difficult to prove anything unless there was an accident. And if there was an accident you can always blame a sudden gust of wind or something. Still much easier to just have a C1 Mavic 3 original or classic! Then you don't have to worry about such matters at all. The Pro really is not such a groundbreaking upgrade that it makes up for its C2 classification.
But as I said before, it will likely end up being your responsibility to prove that you’re allowed to be doing what you’re doing, and not on them to prove that you’re not allowed to be doing what you’re doing. Better to not risk it I think.