http://www.harmonycedar.com/images/truemission-darkcherry-front-500.jpg from 
http://www.harmonycedar.com/cedar-chest-mission-dark-cherry.htm

So what about something like this, sized in the twin model, 64*24*20.. only with pull-out beams, and a flip over top that rests on these pull-outs.. so you could open the lid one way to get inside the chest, or pull back the uppermost wood top th other way to create an extension of the bed.. so now you would sleep at night without positioning yourself over a hot engine bay, good for hot summer night camping and traveling.. or if a professional basket ball player wants to spend the night in your vanagon because his midget wife kicked him out of her little bed... he'd be okay with the length... 

So you could fit four-ton jacks, wrenches, motor oil, filters et ... on one side, and with the use of dividors put you bedding and extra jackets and things on the other side... would be a lot easier than trying to get anything from under the rear seat... I hate accessing that area... hence I'm just going to move ALL of my batteries over there...