At any rate I'm not seeing the pickup truck's rear axle being light. Balancing the load in between the tow vehicle and the trailer is important if it's at all possible. JMHO
I have seen a number of instances where a pickup with no weight in the bed, has had poor traction--putting the weight in the truck (people, sand bags, etc--has solved the problem.
Certainly, one should not overload the boat / trailer or truck. For us a SUV is far more utilitarian, for others the truck (sometimes with camper or shell) works better for the intended use.