IMO something that is vital is an automatic external defibrillator (AED). If you are somewhere remote, have no cell phone signal, or are more than 10 minutes away from EMS, an AED might well save your life of you have a cardiac event.
No they are not cheap. But what's your life worth? If your heart stops, you have about 10 minutes before irreversible brain damage occurs. I bet all of us have been on remote stretches of highway with no cell phone signal. Certainly many remote campsites have no cell coverage.
Take a CPR course and take an AED with you on your trip.