Traffic Pilot
I have a TomTom GO 530 so the menu may differ from yours.
If I hit "Change preferences" then the ">" icon 3 times, it gives an "Automatic zooming" icon. This allows me to disable the auto zoom in Driving View.
I've stored navaids as POI's on it & have used it when SLF on 737's & I reckon it is capable of giving you a pretty accurate fix but that's from an ATCO's point of view , not a pilot's
In any case, it's got to be better than nothing !