Because I don't see it listed here yet, I found the following worked for me:

Now, when I press the button to hide the top bar, the toolbar is also hidden, giving me a properly fullscreen terminal.

Ctrl-backspace still brings up the Expose view for app-switching.

I don't yet know a key combination to restore the top and bottom bars - so if anyone can help me out, that would be useful - doing it by script seems a bit extreme (although they come up by default on a new terminal, which seems sensible).

(Oh, and I already remapped the pgup, pgdn, etc keys to various hardware keys - the solutions for that linked elsewhere worked for me).