....just a thought: IF anyone finds it, isn't your drone registered to you only, via your controller (paired) ? Ie. it can't be flown by anyone but the person with the controller it is registered to, no? Also, does DJI have a way of disabling (suspending registration temporarily) your drone, and keeping track of any "geo-connection" if someone who found your drone fires it up? If DJI does not have this in place, it would be a fabulous feature to offer their drone buyers!
the z dimension (elevation):
....there are mapping platforms that map literally everything "protruding from the ground" at extremely high resolution (at the centimeter, 5 centimeter, 10 centimeter etc resolution per ranged pixel). The sensing device is called LiDAR. Many areas of the US (and now, Canada and Britain) are already mapped (especially coastlines, flood-planes, urban areas & cities, and sensitive forested areas). All the data is available as public domain coverages. So, using the z (elevation) data from the 3D LiDAR coverage, a KML file can be extracted that would give the mission planner precise z elevations over every tree, built structure, antenna, tower and protrusion above the ground. Google Earth Pro only provides the "bare ground" terrain model, not the elevations of all structures and biomass above bare ground, remember (but, as shown earlier, this is an excellent starting point to mission plan!). The only thing that LiDAR would (may not) not provide, would be 3D power lines strung out between the poles/towers.
IF a LiDAR overflight was done over your search target range, you would be able to pin-point the actual tree/structure/shrub/pole/tower/fence your drone would have hit first, along your flight line plugging in your original flight plan elevation number as a compare.
