Bentley really didn't come up with anything but the tech's procedures to reset the odometer. It did have a service bulletin on Anti-Theft Immobilizer for 2000's, but that really doesn't directly confirm that 1999 doesn't have an immobilizer.
But the immobilizer also would include matching the existing keys.
I thought about it and my Scangauge would work for your needs if you can't get the OEM to work properly because of lack of VW service folks.
You do set up the gas tank size on initial setup and when you fill up you tell it that the tank is full, then you could use the x-gauge portion to set up the "how much gas is left" or "how many miles left in tank" (assuming you have calibrated the gauge). But it's standard presets show Tach and MPH.
Q's about my new ScanGauge II
I would check out that Ross Tech link, but that would cost a bit as well - but being as remote as you are, it might be wise to invest in one. Hate to say it, but the scangauge is supposed to be able to pull codes and clear them as well. Just not the tuning that the VAG Com can do.