When in non-full-screen mode, Safari lets me use the ⌘+| shortcut or View > Hide Toolbar to hide the URL and search bar, etc. However, when I'm in Full Screen mode, this option is greyed out. Is there any way I can hide it without exiting Full Screen?
Enter full screen mode, right-click anywhere around the address bar then click "Hide Toolbar" in the menu that appears.
Although next time you enter full screen mode the toolbar comes back.