Taking this idea seriously for a moment, since the topic is "what to do with these losses that occur over deep water when nobody is in contact ..."
You'll want a buffer zone for coastal cities/airports that have approach paths over water. (12 miles, 10 miles, 20 miles?)
Or, consider a dual parameter trigger such as
Over water**
AND
Above FL 180
** How do you define "water" that fits this model?
An ocean?
A Sea?
A great lake?
Water deeper than 100 fathoms?
What nav system calculates this figure?
How does this system figure into the MEL for a launch?
How much of your fleet has to have it?
What is the operational impact if this system is down? Abort depending upon route?