Real world load weight, how much are you towing?

I off haul off of construction sites a lot and many times the local "public" scale is the dump or quarry I'm hauling the material to. With a 17 yard dump box on the truck many contactors don't want to believe me when I say that I’ve got a full load on because the box is only 2/3’s full. Now I just show them the readout on my onboard scale and tell them to stop loading me.