I used the Harbor Freight Folding Trailer #90154. It’s 4×8 ft, however, I shortened it about 20 inches or so.
It was my desire to not be banging my shins into the trailer’s end crossbar, tail lights, or license plate.
I did re-color the trailer with John Deere Green paint. It’s durable, easy to apply, and you can always find a retailer that carries it. The original red paint does require a bit preparation before it is painted with another color.