Mechanical safety is about a host of things but largely its about PROPER WEIGHT DISTRIBUTION! MUCH MORE SO THAN THE SIZE OF THE TRUCK. ie each axle of TV and the trailer axles and the TW if its not a 5er.
Still too many blind trying to lead the blind. I solved all my problems when I got a bigger truck. No you didn't you just masked them with a heavier truck and a stiffer suspension. A bigger truck provides a little more room for the uniformed oblivious. Proper safety involves weighing axles regardless of what truck. You don't short cut safety by simply buying a bigger truck even if to this point you have towed that way. Obviously I am not talking about a dually towing a golf caddy nor a Chevette towing a 40' bunkhouse. And I am not saying you have to weigh every load every time but I am trying to make a point of weighing axles figuring TW and more is safety not just buying a bigger truck.