Apart from matured and highly reliable commercial satellite-based services, WSPR can be another 'DIY/experimental' alternative for broadcasting your location from wilderness. See examples for balloon, photo and ocean floater, photo.
WSPR is an very low speed mode with 2x to 3x dB SNR advantage over many other digi-modes. Range of a few hundreds to a few thousands km are possible with a few watts, or less, of HF transmission power.
A global network of receiving stations are already setup.
EDIT: If broadcasting position and/or maintaining telecommunication are essential for 'safety' reasons, mature commercial satellite equipment should be used. As said, WSPR is 'DIY/experimental'.
Some satellite system uses a large number of LEO (Low Earth Orbit) satellites (Iridium etc.) and would have better coverage probability for partially sky view obstructed locations. Satellites can appear at higher elevation (near Zenith), multiple and time-varying sky positions. If you wait a while, one of the many satellites may move to a position in sky with direct line-of-sight toward you.
Depending on where you are on Earth, those use equator geo-sync satellites (Inmarsat etc.) demand "much more openness" sky view as satellite may appear at fixed and lower elevation (toward South and toward horizon) positions.
Even LEO satellite may have better coverage, no satellite works at too deep and too narrow valleys.
Examples of mature commercial equipment for 'safety' (non DIY/Hobby) uses 1 2 3