Saw this Harley on the back of a 5er yesterday

Think about what happens when the rear of the 5th wheel tries to squat from the hitch weight of your swivel-wheel trailer. If it's receiver mounted (single or multiple receivers), the female (5th wheel mounted) part of the receiver will try to tilt down at the rear, but it's being restrained by the male (swivel-wheel trailer mounted) "stinger" that slides into it. The more the female part of the receiver tilts down, the more weight that's being transferred onto the swivel wheel(s). That restraining force imposed by the receiver mechanism and swivel wheel(s) limits the weight transfer off the pin, so it can't transfer as much pin weight as the same weight if it were overhung or cantilevered where there's nothing restraining the weight transfer.

Rusty