The lightest duty one I've seen is a Hand truck with a ball mounted to it.
I bought one from CL for $20.00 it was advertised as a 1000 pound capacity. It had an adjustable height ball so I thought it was one of the heavier duty models rated for 1000 pound tongue weight. Turned out it's was the lightest duty one sold on Amazon rated for 1000 pound total trailer weight, 150 pound tongue weight. The people who bought it from Amazon gave it very poor reviews b/c of the misleading weight rating.
It works for my needs but I'm thinking I may rebuild it with some 1" spindles I have from an old axle, hubs and 4.80/8 tires.