I have pulled my 38 foot 5th wheel with 2 duallys (3500 & 4500) and 2 single rear wheel (2500 & F350)
I feel more comfortable towing with the duallys, especially the 4500 I have currently. The stablitiy of the dual rear wheels is noticeable. The biggest factor is stopping...The extra set of tires keeps the trailer from pushing the truck around in a panic stop.
Advise him to go with the largest truck he can afford. A one ton dually at minimum will be safer and last longer than a 3/4 ton.
If he plans to travel a lot he may want to consider a MDT or HDT. The HDT is the ultimate 5th wheel hauler.
