Why not get a offline satnav app? I run co-pilot on my android and it only needs a net connection for traffic updates. All maps for Europe are already installed.
Why can't you run the iPad mini through a reference head unit which has a digital out to the audison. PS make sure you get your audison properly calibrated. Takes between half to a full day.
Username: The Bounty Bar Kid
Location M25 junction 7 (near Coulsdon, Surrey)
Obd2 software: Torque, Dash Command and the free scan tool one which came with it.