I'd love to do something like this one:
http://www.expeditionportal.com/forum/threads/47516-LATEST-PROJECT-Truck-Drawers-Sleeping-Platform
But hesitate to do it in the Suburban due to the difficult removal and limited space for our dogs on top (65-85lb Labs). I also would want it small enough to use with the third row seat installed since we have the captains in the second row. It's pretty common for us to need to seat at least 5 (3 kids).
Right now I am fantasizing about copying that design for my truck bed trailer, which I think it would work best in. I have only used it for non-camping related activities once so less worry about having to remove them. And with having a topper, even though it has swing up doors on the sides, it would make it much easier to access gear.
I'm thinking, recovery / tools, fluids on one side. Kitchen stuff including pots and pans, dishes, utensils and durable food like cans and spices on the other. That's the stuff that would likely stay in the trailer when camping / traveling since I set the kitchen up around it. The rest we keep in Action Packers or ice cooler which would fit nicely on top and easy to access the one's up in the front with the sliding top.
Right now it's usually one action packer for non refrigerated food, one for utensils, towels, trashbags, plates and cooking stuff. Then one for lanterns and general campsite stuff. Finally, one for each tent we are using. So if it's the wife and I we only need the one packer for our tent stuff, if the kids are along in a second tent, two. So a drawer system would cut down on my need for action packers and keep stuff more available than digging through boxes.
Without the water and plumbing and stuff. Maybe just a gravity flow water tank mounted under the bed. To help with center of gravity and be able to bring along 25-30 gallons which would sustain us for a solid week (cooking, cleaning, washing off, dog water). Right now we have 2 5 Gal collapsibles and have to find a spot to refill about every two days, without showers. No water heater needed, only get whore's bath at most while camping, unless we happen to be in a state park.