I used the solid plastic boxes at first, but found I had a lot of dead space between them.
So I got some ebags packing cubes. They come in a bunch of colors and sizes, so you can easily identify what is what. They are soft, so they don't take up more space than what is inside of them. They allow for air flow in the contents so clothes don't get must smelly.
I find I can fit more in them and they can fit into more spaces than the hard crates.
1975 American Clipper RV with Dodge 360 (photo in profile)
1998 American Clipper Fold n Roll Folding Trailer
Both born in Morgan Hill, CA to Irv Perch (Daddy of the Aristocrat trailers)