I live in a apt with a garage but I use the side of it as well and I use these toughbuilt I think the name is I got at lowes a few years back that I rigged a bit myself so they would hold up better to weather. there pricey but look good I paid $400each for 3 of them since I wanted space fast at the time but there 6ft wide 5ft deep and almost 5ft tall thick plastic. they have a lid and two front doors that open to a big space inside but I rigged them first with steel plates I found scrapping and attached them to it for a base that with the straps I ran down the sides it wont blow away and is lifted just enough I can still get a pallet in and out easy. this way I can store a pallet box in each one and have room for anything I may want to cram in as well to one side.
there meant to store mowers and such even has crappy lock hole things on the doors were they come together which I just use a bike lock lol I would not spend so much now but at the time it was a fast easy solution which I am not sure if they sell them still but sure they do similar but the idea is it keeps it clean good looking and less chance people will steal stuff cause there not fortknox but works