At a truck scale (landfill, truckstop, materials yard, ect.) weigh the fully loaded tow vehicle alone first. Then hitch up the loaded trailer and pull the tow vehicle onto the scale leaving the trailer off the scale. the difference in the weight is your tongue weight. Then pull the whole load on to the scale and you have the total weight. Doing this fully loaded for a trip is beneficial as you now have the vehicle weight, tongue weight and trailer weight. One cannot safely size tow equipment (hitches, axles, tires, tow vehicle) without these numbers.