Over the years, through trial and error ... ok, mostly error, I've developed a very workable storage system for the backs of my mini-vans and now suburban.
Michael and Morgan have both asked me for details. Michael with his new Tahoe and Morgan with his pick-up truck, want to do something similar.
Not going to give exact measurements, because your needs and drawers will differ.
sheet of 1/8 inch plywood for box base
sheet of 1/2 inch plywood for box top
2 1x10's for box sides and center support
2 rubbermaid underbed wheeled storage containers with tops
2 low profile coke trays
Notice in the pix that my drawers are slightly off center, so that I can store brooms, mops, rakes and a couple of extra folding chairs on the left side of drawers. On the right side of box is space for awning rails, supports, and rod.
Notice the height of the box allows me to carry a small ladder on top of one of the storage containers. And two folding tables (bungi-corded together at the handles on another.
I removed the third seat in the suburban, so my box runs from right behind the second seat, almost to the rear hatch. I say almost, because I left room for the two low-profile plastic coke trays, in which I carry a multitude of easy access stuff.
In our mini-van, we removed one of the second row Captain chairs and third seat, and made a box with two lengths.
We carpeted ... ok Pam carpeted... the top of the storage boxes in a color coded carpet. We also painted the wood to match.
This system allows you to carry anything/everything you want on top of the box, but still have ready access to the drawers.
Pulling the drawer half-way out allows access, but also gives you a work surface. It's easy to pull the draw all the way out (it's on wheels, after all), turn it end-for-end and reinsert.
As I said, it works for us ... and works well ... because, after all, I carry enough stuff to completely rebuild the trailer if need be.