I think you will have a nice little trailer to work with. You will have a great overland rig once your done. Like the idea of putting the water tank there. But I also have some concerns with the way you have your leaf springs mounted. On my XJ the previous owner used longer shackles to add 2"s of lift to the leaf spring (with add a leaf) to obtain 4.5"s of lift. The first few times I needed to make a quick correction to avoid someone the rear end of my jeep got very squirrelly. I am used to it now and drive as carefully as I can, but some day when the funds are available I will buy 3.5" lift leaf springs and 1" lift shackles to correct the issue. I wonder if the trailer would act the same way? It would not be to hard to make mounts to raise up the frame instead of the long shackle. On my trailer build I feel the 31" tires should provided plenty of clearance for taking it off road.