How do you like your 2019 RAM 1500?

Aren't you forgetin about the SAE J2807 towing specification, which most trucks (Ford Ram, Toyota, Chevy and GMC...not sure about Nissan) are designed to meet? The spec includes 300 lbs for the Driver and Passenger (I know its not enough but its something) and 100 lbs for aftermarket WD hitch. So in your example above you should remove 300 lbs for the driver and skinny passenger and you should remover the 100 lbs for the hitch because its already included in the numbers. So technically he's got an extra 400 lbs of payload and should be fine. I also think your estimate of the tongue weight may be a tad high too and its something that he can control by properly distributing his weight.