Gents and ladies,
Do not put vital info in your GPS units.
Nor mark them on a map.
Too easy to lose them to a hostile force.
The they have corroborating evidence against you.
The best answer I’ve found? If you must keep it all together?
The little black book. The old phone address book everyone had before phones became smart.
First, change to UTM coordinates, then change those into telephone numbers, being sure to match up the area codes. Need a few more numbers? Make it a business number with extension numbers.
Erase all tracks on your GPS that correspond.
Want to leave breadcrumbs for family?
Become romantic, mark a state map with places you’ve been with your significant other, picnic with “lisa” 2008. Then mark it with places yet to go, canoe trip 2015, etc.
Food caches are picnics, weapons are arrowheads found, etc.
If you must leave an “open” list, make it part of your geocaching hobby. Build an innocent list with public caches, including the contents, leaving a couple with no contents, then insert your location into/as one of the empty caches listed. Leave the list for ‘grandson johnny’ to finish as a reminder of your games together.