I have occasionally had to be by myself for a week or two while my wife travels to visit family, and that has never been a problem. I always know her itinerary and can follow along from a distance, and she always makes certain to stock the house with everything I will need while she is away...and it sounds like you have a workable plan including some helpful preparations.

Apart from that and if my wife were to die before me, I would not even attempt to live alone. I would immediately ask for help in finding a live-in caregiver, an assisted-living situation, group home or whatever.