Just to update: we've taken the Suburban camping twice lately.
Right after my last post I finished the "bunks". We slept a family of 4 in the back if the Suburban. I'm still amazed by it. Each person had a full length bed with about 22 inches in width and 22 inches in height for turning over. I was thinking of submarine beds as I built them.
I had a camp toilet positioned right behind the front passenger seat that the ladies could use at night.
We rigged a tarp to cover the Suburban to create some dry space right outside the truck in case it rained (and it did). But, I replicated the same space as some of the awnings you can buy for SUVs.
Finally, I have a hatch tent that fits my VW Westy and oddly (to me at least) it fit the Suburban perfectly. With a solar shower bag laying on top of the Suburban right next to the hatch door, you can run the hose between the hatch and truck, and then shower inside the hatch tent.
I think a Suburban outfitted with an awning, rear sliding drawer system with bed on top, and then whatever comforts you want to add like showers and camp toilets would work great. I'm surprised I don't see more people build these. Seems like it would fit the needs nicely for so many people. Quiet highway ride, decent fuel economy, very spacious, and could be quite "stealthy" for certain sleeping situations.