I can tell you that you will want something across the front of those milk crates to keep eggs from rolling out. I just screwed a 1x4" board into the plastic. I've used those on many occasions and they work just fine for nest boxes.
We use these, and I agree with speckledhen. Make sure you put a board or something similar across the front to keep the eggs in. My girls seem to like these boxes. I really like your use of the closet shelving at the entrances.
Some of mine used to like them right side up, too. I've even just sat them on the floor on occasion. They do work just fine and are easy to clean. I'm always looking for cheap milk crates for various purposes.
I've taken milk crates,sat them flat and cut an entrance on one side so the bird can climb in and lay like in a nest. Throw some bedding in there and bamm, bobs your uncle