J.B.
Do you have an attic? I stored my holiday decorations in my basement under the stairs for years but realized that that space was better suited for things that I need to get to more than once a year, so now that's where the kids' clothes go for off-size or off-season storage and the attic houses all of the seasonal decor.
Assuming that you cram as much stuff into each box as you can I can't imagine that a different storage container would magically cut down on the space you need, but maybe moving it to a more out-of-the way place like the attic or garage if you have those spaces. In our garage, by husband put some plywood down over the rafters and gave us lots more storage space that way for summer things.