How can I obscure what I am using to run my site?
You can't hide it completely. Most of what's needed to do it, would require hacking core. The biggest tell, is the Drupal JavaScript variable which is readable from the front page, or any page for that matter.

If you want to improve your sites security by hiding that it's a Drupal site, your effort is better spent on code reviews than it is on trying to hide the fact that the site is made with Drupal.