Once you can get it up in the air then the higher you can go you're doubling your storage in a linear fashion. Hoist one of those trucks to 50 meters (perhaps you have a handy cliff in your backyard) and you've stored as much as the ten trucks did at 5 meters.
So yeah scale seems hard, but the low technology/materials requirements and potential for gradual scale-up make this worthy of deep investigation. I think there's a lot of wandering off into dead-ends as far as limitations go though - Solutions that depend on a lot of concrete pouring, for example, are a no-go if the end goal is reducing atmospheric carbon.