When we got our Carson Trailer custom car hauler a year ago, we ordered it with the minimum of accessories but with the biggest, buffest frame and undercarriage we could—just the way we'd specify a brand-new 4x4 that we were immediately going to modify.
Our Carson trailer came with an extremely sturdy steel frame, an 18-foot by 102-inch wooden deck with steel drive-over fenders, dual 8-lug axles (both outfitted with electric trailer brakes), and side-loader ramps without a dovetail on the trailer deck—to keep ground clearance at a maximum in the back. Accessories on our trailer included a spare tire and a cargo box, and that was about it. But we were about to change that by adding some custom wheels and tires, a winch, an LED deck light, a sealed battery inside an aluminum battery box, and some brand-new straps correctly measured and specified for our trailer's D-ring locations.
Are we done adding to our trailer? Well, probably as "done" as we are with modifying our project trucks.