Is such a low cargo carrying capacity possible?

subtract the dry weight from the GVWR
That gives you a total of 1443 lbs of stuff.
Some of that stuff will be water at about 8 lbs a gallon equals abut 290 lbs. 40 lbs of propane, maybe grey or black water, a spare tire and even the leveling jacks if an option etc you have the remainder for your stuff.