Thought I'd post up some of the initial mods to my x19.
When I bought it, I came with dual 6v batteries, but they were in individual boxes and the setup was a little flimsy/messy. I bought a larger box designed for dual batteries and welded up a new tray to fit the longer box.
Next, I wanted some cargo space on the rear, but the factory bumper is too thin, and the flip down cargo trays just u-bolt on and shipping was around $250. So, I went to my local trailer shop with a design I drew up. They made me a new 3x3 bumper with 3/16 wall thickness, and added dual receiver slots in both the ip and down position. Then they made a cargo rack that fits vertically so the bunks still open and the brake lights are visible, or horizontally so I can store some firewood/generator/etc