Create sandbox site from existing blogs


I’m creating an MU blog with Multi-DB. I have only a few blogs but lots of content, plugins, themes and some customization. I would like to create an identical sandbox blog on a different domain (not sub-domain) to test new things before using them on the live site. Is there a way to just copy the entire existing WP installation to a new sandbox site?

I just read and could probably figure out how to change the databases. But can’t imagine coping all the site folders to be as simple as copy/paste. However, if I could do that, I would still need to create and update the databases, and change what else?