If you are worried about that, you have to be really careful with OPSEC.

The "look over your shoulder" attack is omni-present. (Also easier to prevent with paper, in general, than with a larger computer screen.)

A simple safe will stop most prying people. And if you die... Well, you are dead... there ain't much stopping anyone at that point.

Keeping secrets is hard. Very hard. There's a reason for the most part... I don't bother, except if/when I need to, and even then, if they can be timed out, all the better.

Paper also has a big benefit in that we know how to destroy it. :)

... Simple things are often best. Understanding how your system will bend/break is critical in security situations.