My off the beaten path navigation is done using an otherwise fairly useless iPad (version 1) running HEMA maps supplemented by detailed maps from memory map, gps signal comes from an aviation quality external Bluetooth GPS/glonass receiver. Works well for us and as it is not bound to the vehicle trip planning can be done anywhere comfy.
Personally think that sat nav built into vehicles is a bad idea because they will be quickly eclipsed by mainstream consumer tech (as is the case with mine).
Just gotta motivate myself to fit a gvif and some additional cameras (rear, front, under) and my screen will be slightly useful !

