I know it is just me, but I do not feel comfortable storing supplies anywhere but on my property. That said we do have stores on all three levels of the house. Stores in the garage are kept on an exterior wall. Should the building collapse be it from tornado or earthquake I will know where to start looking, and hopefully can get access.
My preference is to keep things hidden in plain sight. Boxes marked "Baby Clothes" or "Tax Records 2015". Throw a few things on the top to cover up what is really inside. Put some old magazines on top of a box of canned goods, and they will weigh about the same.