Context plays a huge factor here. Depends a lot on which country you’re being prosecuted, how much effort is people putting in catching you and gathering your evidence, and what kind of resources you can count with.

Personally, I’m not too tech savvy so I’d take the bury it in the woods option even if you say it can get corroded. There’s many things that can happen to it, depending on the weather, environmental policies (cross your fingers they won’t be selling the land for development while you’re away), and what you can afford to store your drives in. I believe it’s possible to protect the cache well enough if you ziplock them carefully and then find a Tupperware container, perhaps put that inside a larger wooden box or a tin to protect against crushing you should be good. Hell you can even cover the Tupperware containers in cement so it would look like you are burying rocks. But, do you have access to these things? Do you have the time?

Another option is to hide the cache similarly protected in some architectural nook you know of, perhaps at a friend or relative’s house- some places have space under houses. Or perhaps you know how to crawl in some wall space or similar. The challenge here is returning to it, because the landlord (your friend) may be gone, dead or else by the time you’re out. The property may be bulldozed and sold, who knows.