I built mine from store bought utility shelves from Sam's and cut it up to fit. Tilt the shelf slightly so everything slides to the inside for easy access.
Use cardboard, not plastic bins. You can get them in any reasonable size.
The plastic works well but is EXTREMELY noisy over bumps etc. Cardboard bins can be had from Grainger for less $ than plastic too. Get the cardboard first, then built the shelves to fit them.
Everyday items should be placed within reach of the doors. Keep ladders out of the inside of the van - at least while ur using it. I have a 4 footer standing up in mine, a six on one side, an eight on the other. A 10' and a 16' stepladder on the top.
The key is not to be crawling through the van for a 1 gang cut in box and a hand full of wirenuts. (by the way I've also seen gas mileage improve 1.5 mpg by using Mobil One synthetic oil. Doesn't sound like a lot but when ur getting 9mpg, 10.5 looks real good.)
