I've also been wanting to use an Android tab to show all the readouts instead of installing actual gauges for awhile now. I finally found the perfect mount (in my opinion) and thought I'd share it here:
http://www.proclipusa.com/brodit-veh...812-19052.aspx
IMO it's in the perfect position (above the glovebox) not blocking part of the windshield, hindering operation of the vehicle, or in the way of a passenger. They've also got specific mounts for each type of tablet.