Good post! Here are some more ideas...

Write it down and keep it in a safe. I go beyond the 16 minimum. Probably 25 or 30 maybe shorter if your data is really random. Just a simple habit like this puts you in total control of your money.

Over the years I have collected lots of random data sources I can copy in pieces but be very careful doing that. Add your own entropy to that data at least. Base 58 is nice because it leaves out some letters that look like numbers.

Want to update your living-will? Put a copy in a family members safe.