I have not added anything, yet. I am mounting the propane tank under the left front corner of the box, and a gray water tank on the other side. Those mounts will also add structure for the items sitting over them inside the box. The fridge is on one side, and the bathroom on the other. I am trying very hard to keep the back of the box wide open. It will have some type of seating but the plan is to have it fold up against the wall. I want to haul my bike back there. I hate having stuff mounted outside in the elements and available for thievery.