Done similar for my Defender, but on the cheap, ie free, and not as high!!
School table cut down, I kept meaning to swap the table top to reach each side, but honestly, the sides work well for storing, on the right, my cooker and two chairs, on the left a tow rope and a couple of strops and shackles in a box. I used Weldmesh fence panel for the dog guard. I could easily add a frame to put a higher shelf in, but this works for me.
Did similar when I had the Disco, but with fold-out wooden sections to make a full bed for camping ..
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