So I use 55 gallon drums, steel with clamping ring tops. I think they are airtight. I bought mine for $12.00 each at a surplus store. The owner was making jokes because he bought 50 of them for $5.00ea. Just make sure there food grade and not old oil drums and they need to have removable lids. Just for the record, there not only mice proof but my friend has his in a barn and they are Bear proof too! I have discovered that with basics in mind, one drum holds enough beans and rice to last each person a year.
Keep in mind that other drums with salt, sugar and coffee and other go alongs are necessary. I use a foodsaver vacuum packer for a lot too.
Even the old dented up drums are good for things like toilet paper, as long as the lids fit and can be sealed your good to go.
How much to store? I just keep going, I figure that family members will come to my place when things get dicey. I just keep going but I started a long time ago so now it’s all about rotation. I don’t think it’s a good idea to bury them as rust would win out in the long run.
My father use to say ” your worth what you know son” so I have learned how to make liquor, beer,process meat and grow food. I just ordered tobacco seeds, plan on a lot of that, barterable production.
Good luck all..