Used the 24" deep shelving unit from Home Depot. Everything else is pretty much the same except for the ecuboard, which I painted with a couple of coats of weatherproof paint to seal it from moisture. I was going to use the markerboard that was suggested, but Home Depot only had the 2x4 sheets for $11 a piece instead of the $24 for 4 deal that was posted on their web site. Oddly, it fits two 32qt Sterilite tubs per shelf with no modification to the legs even though, based on the measurements, it shouldn't. I guess it's because the tub measurements are including the tops which are not being used.

Still waiting on heat tape to show up, then I'll level all the shelves, set the clearance, add the heat tape, screw them together, and start filling it up.