Here's the pictures. You can store the mattress behind the open doors of the bulkhead when hauling 3 skids, or in front of the refrigerator. Doors with bungy straps are behind wheel wells when done right. The only draw back is 3 skids overnight. A guy can throw a mattress on top of the load, but my wife will not sleep that way, so we make sure 3 skid loads are no more than 600 mile runs and unload when we get there. If you can get your wife to climb on top of the loads you both could sleep, if waiting to unload.
I have 3 load bars, when having 2 skids, so load doesn't damage doors on bulk head. The load bar picture shows that you can place a board on load bars with mattress and have 2 beds, for separate beds, when laid over with no load. Make sure that you have a bottom plate so skids cannot continue to driver on 3 skid loads. You will be using 3 straps, but I still made sure the bottom plate was installed and top plate. If straps break it gives a little added protection.
I have bought a new truck D unit, and will pick it up in 6 weeks, but I wanted to see what it was like to live in a van. Been in the sprinter 8 months. I have a small fleet 5 units and figured my 2 H/W van teams would benefit from me knowing what they go through when driving a van. I will have 2 units available soon, drivers getting new equipment. I think the sprinter is a very good van. I have 370,000 miles on sprinter engine, nothing needed, but new water pump. Hope this helps those that can't or don't want to be out the money for someone else to build. The way the sprinter is made the side pieces are the hardest to make, as they are curved, rest is easy. Bed folds down on boxes (that can be used for storage) so bed is not on the floor. The refrigerator sets on top of cabinet that has a porta potty for wife, keeping it out of sight. The microwave is mounted to wall and refrigerator, and the computer printer is mounted to microwave by industerial strength velcro. If using microwave always start engine until your finished as it will run batteries down fast if not running. We were actually very comfortable in this set up. We have a 17 in flat screen tv & DVD player that is really light weight that we store in computer bag, when not used. We have a hanger for it on wall when laid over.
