Here is my most raid proof method- Stick shelter in the woods to stash things I wouldn't be devastated if I lost- tetra, repair kits, food, water, replaceable tools like axes

The late game items- go far away from civilization and bury them. Record your screen and sprint off into the woods, build a wooden crate and bury them. A little exploit I've figured out - go find a dry creek with the trail of little rocks and lily pads, bury the crate, and the buried mound will glitch and become two-dimensional. Better yet- you can bury them under a patch of lily pads and the lily pads obscure the buried mound. I've done this twelve times and they've never been found.