This is my setup which automatically binds Deluge to the IP assigned by the OpenVPN server.
Assumes OpenVPN client uses the tun0 interface.
It's theoretically subject to race conditions, but have not had problems so far. There's probably a better way to do this, but I'm no systemd whiz.
Requires sponge be present (apt-get install sponge); was running into permissions problems when allowing sed to create a temp file.
Suggestions welcome!