Crafty solution for your own use, but I wouldn't suggest using an anonymous proxy to others unless they had a solid understanding of the ramifications.

There is no expectation of privacy, the owner of the proxy has a copy of everything you look at.  Motivations of proxy owners vary widely, some want to steal your banking password, but they all have the means and right to do whatever they want with your traffic.   Sure, it's all public record, but no one should know what I am working on but me, my client, their client.

It may not matter most of the time, and the odds may appear long, but I don't want to take the chance ever, not with any client or their customer.  I've worked on properties owned by celebrities before, and I wouldn't ever want a deal to go south because of ill-timed publicity.  Imagine tmz.com publishes a rumor about an NFL player selling a business, all based on a "tip" from an anonymous proxy owner.