My truck is set up as follows: Ram 5500 crew cab 4x4 with a 9’ aluminum flatbed with (4) tool boxes. 40,000lb rated gooseneck hitch and a 20,000lb rated bumper pull hitch. It weighs 10,500lbs with a tank of fuel.
Trailer: Kaufman 38,500lb 35’ gooseneck with 3” ball. Max load capacity is 14 tons. Typical load is 12 tons of hay or a 10,000lb-20,000lb farm tractor.
I am ordering a 20,000lb deck over dump trailer as soon as they start making them again (due to Covid, most have discontinued deck over dumps).
I do both hand calc mileage and the trucks computer and so far the computer is spot on.