Get a new, longer piece of steel. Paint it red.
Here's a copy of a post on my similar but larger kit trailer, which had a tongue that could be re-drilled and slid forward:
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Northern Tool had a 4x8 folding utility trailer kit on sale for $179 (half the usual price). With wheels, tires, and shipping it came to about $350. I had some Kee-Klamps (steel fittings like SpeedRail but way heavy) lying around so I got some top-rail tubing and built the rack (another $50-75). Since my boat's wider than the trailer frame, I had to lower the trailer fenders a bit and build the rack to clear them, wider than the frame.
The only other mod was to drill new holes in the tongue so I could extend it. The rollers are PVC pipe. The rack unbolts and lifts off in about 10-15 minutes. I also made a plywood bed and slat sides for utility use.