Very nice setup bjmsam.
Years ago I'd done something very similar with a Mitsubishi Expo, a car about the size of our current '06 RAV4, but with two variations.
First, I mounted the bed floor on a frame that raised it about 8 inches. That gave me lots of storage underneath accessible from either rear door or the back. On 4.3 RAV4 it would also allow access to the rear underfloor storage.
Second, I mounted two 12V computer fans in a thin piece of plywood that fit the rear window nice and snug when I rolled the window up to it. I covered them with screen and had them switched so I could run one or both. Used the rig all one summer while traveling with my dyno business. Then I upgraded to a pickup with a slide-in camper for all the comforts of home.