It looks like chrome's javascript interface exposes options that the command line doesn't. Or else I'm overlooking something, because I couldn't find a way to to hide the header and footer (which shows the date, title, url, and page number) using the command line. But this project does hide the header and footer.

I can't use an externally hosted service like this because some of my URLs are non-public. So when the user requests a PDF, I render the HTML to a temp file on the server, invoke chrome via command line, and serve up the converted PDF.