I came up with a way to get some more interior storage room out of this thing. There is just enough room in the bed area to sit up in (I'm 6'1"), so I didn't want to place cabinets in there.
But......
I noticed that I had just over 12" between the front of the fender where the trailer body gets wider (it slims down underneath due to the tires) and the old "firewall" that separated the kitchen compartment from the interior area. Amazingly my water tanks are 12" wide. I moved the tanks out to the sides and into this void/dead space. I then moved the "firewall" behind the water tanks. I relocated the battery into another dead space behind the fender. This allows for drawers to be placed in the center of the interior area.
I will install removable panels (for looks) to hide and allow access to the tanks from the inside area. Now that the tanks are "inside" I believe the interior heater will keep the tanks from freezing. The heat would not be used while moving from camp to camp, but I do not think the interior will get to freezing temps that quickly and allow the sloshing water (due to vehicle movement) to freeze.
I also added shelves on the non-door side. These will have raised lips to keep items from falling.
It is hard to see (it's in yellow), but I will use the interior void above the fenders as long storage compartments (perfect for rifles). The compartments unfortunatley will be under the thin mattress. In order to access them, one would need to roll back the side of the mattress, and then lift the trap door. It's not ideal, but it's free long storage.
I believe I have solved the problem of what to do with the rear door. Keep in mind that this trailer is set up to use for weeks at a time. I as a Jeep owner take my doors on and off with the weather. I have full hard doors that can't be stored on the Jeep when off. I plan on buying a second set of door hinge hangers and attaching them to the rear trailer door. This will allow me to take the doors off of the Jeep and hang them the same way they hang on the Jeep. I will fab up a mount in the center with the same door striker latches used on the Jeep for the doors to latch onto (so they don't swing around). This allows me to hang the doors on the rear door, "close" them onto the striker, and lock them via their key holes to keep them secure/in place.
The doors will be quite high up and close to the rear door and away from stray rocks. If I were to take this on the Rubicon I could see a potential for the doors to possibly see damage. With that said, I don't plan on extreme rockcrawling with this trailer.
I added the Jeep as a reference to how small the trailer really is.