I did just that, thanks for the input. I actually went ahead and discarded the actual query strings being used; so I'm now logging access times, referrers and user agents only.
I agree that an extension may be better, although this may come handy when you're not using your computer or main browser.
Also: don't only promise! Put privacy page right there and explain what you explained here (maybe even in greater details, people love transparency), so every user we'll be able to obtain same information.