I don't think you can do more than just doing what you do. You can aware customers on the front-end that they arn't supposed to save any data on your system the

I don't think you can do more than just doing what you do. You can aware customers on the front-end that they arn't supposed to save any data on your system they are afraid of sharing. I can understand this is difficult from an ethical perspective but I think that as long as you arn't actually stealing data or participating in systems like PRISM you should just be fine.