It seems that one of the most important things to start with is a page right at the top of the box with "IF THIS BOX HAD TO BE OPENED" followed by notes about p

It seems that one of the most important things to start with is a page right at the top of the box with "IF THIS BOX HAD TO BE OPENED" followed by notes about payment for the box, multiple contact methods including through several third parties (friends, family, employers), etc. with mailing addresses, phone numbers, email for each. Heck, include several pre-addressed letters or envelopes with (in the USA) "Forever" stamps already on them. Work from a basis of "mistakes happen, how can I minimize the impact?"