One thing that I sometimes do when I'm uncertain of an ethical decision is to take a majority vote of different ethical systems. If there's a clear majority going one way, then that's useful evidence that whatever my actual moral position, that's what I should do. This reflects that I suspect at some level that humans either have an inherently inconsistent moral framework or we haven't really come up with a good way of articulating what our actual morality is. This works as an approximation.