They take up a lot of space in the house. Will these boxes live ok in a a couple thick 3 mil plastic bags in garage attic where it can get very cold in winter and hot in summer???? Will cardboard stay ok?
You could try putting desiccant packs in the plastic bags, or just punching a several 1/4" holes in them. Make it a long-term project: put a couple of the less desirable ones up there now and see what they look like next spring.
If you put the cars back in them, you can store them at my house
Mine are in tubs from Walmart, the big plastic ones. I built a rail system that the tubs slide into on the garage ceiling. I have the bottom of the tubs marked with black marker on blue tape so I know which one is which.