All of you make great points.
If you bury your cache don’t bother with a pick axe….just build a fire on top and melt through the snow until the ground is loose. As you get closer to cache depth just scrape coals on top. If you can’t risk smoke just stash a bag of charcoal and use it to melt things. As long as the charcoal isn’t right at the site of the bury people will have NO CLUE. Tried it and it works, although I use wood as no one is anywhere near….less to cache.
A pick axe is a pain to cache. If you’re going to do that I’d recommend a cheap crowbar. Even left in the woods unprotected they won’t rust away in any reasonable amount of time. A simple coating and they’re good for a lifetime (not near the coast though).
I’m not sure how bears/wild animals are in your area, but I’ve put test sites out where a plastic bottle filled with rice sat on the surface for a year and nothing bothered it. I’d be worried near parklands as the wildlife are trained to eat from humans and may chew through to investigate. Mine lasted a year, where (by a hunch) I’d say all the smell was pretty much gone.
Bears COULD bite through most cheap stainless canteens. Not one of mine has ever had a scratch (40-50 tested or deployed). Just rinse them before deploy. I also stash them in logs. Did you know that the same log will be there 10 years later !?!?!?!?!?!?!?! (Not Birch though). Useful tip to know.