I have found that some of the small plastic organizers from the big box stores work pretty well. You can build your shelving to accomadate the size organizer you choose, with a lip to hold them in place. Just get some reasonably tough ones like Rubbermaid etc. I fastened 1x2 strips between the organizers to keep them from jamming together from those sudden stops. Then I keep a roll of 2" tape, the blue kind, and a sharpie to write what's in each container. This way you can change it, as you will always be finding a better way.
As for the receps, switches and cover plates, I use plastic bins from Grainger, all labeled by type and color.
I have 3 Rubbermaid totes stacked on top of each other at the head, metal boxes on the bottom, plastic next and cut ins on top (I do a lot of old work). I keep them from tipping with a bungee.
You will always be changing something as you figure out a better way. Sometimes it's good to go thru a section and remove stuff you never use.
The only thing I have not been able to do is make my cargo area speed bump proof. A couple times I have not noticed one and paid for it.
