How do you know he has excessive hitch weight as he has never weighed the combo. Being over a payload number "DOES NOT" mean the vehicle is a unsafe vehicle nor does it mean he is putting anyones lives art risk.
If your silly enough to believe that you shouldn't be driving our countries roads as 100 percent of commercial vehicles out here around hauling/towing you are well over a payload number...if they have one which many older vehicles before '05 may not.
I'm always surprised at RV folks in particular that want to tow a trailer but never weigh anything.
As wiser folks suggested get your tow vehicle front and rear separate axle weights and then you will know what your working with and what to do. If the combo is set up properly with the right hitch I doubt anything will need to be done other than enjoy your rig.