Actually xlegs, you dont have to wait for Dave to film your scenario - because there is a very similar video starring Sienna and called 'Bursting In A Bikini'.
It must be at least a couple of years old now, and therefore maybe not easily available; I don't know as I rarely browse the archives. However, it has a similar storyline, Sienna is sunbathing on the verandah but gets up to pee only to find that somehow the door is locked and she cannot get back in the house.
What I like about this video, in addition to the fact that Sienna wears a very fetching stripey bikini, is that she looks at first to be putting her hand between her legs in the normal crotch holding manner, but on closer inspection
as she walks around, it seems as if she is just placing one finger to touch the region of her clitoris which to me is even more erotic.
I love the idea of women being genuinely turned on by needing to pee.