In the gas vs diesel for towing a fifth wheel argument, diesel will get the preference if your priorities are frequent towing, heavy towing capacity, more mileage, and fuel economy. On the other hand, the gas version is the better choice for the occasional towers who are not going to put lots of miles on their vehicle. In fact, both the versions have their place in the RV-ing community.
Read more: https://outdoorfact.com/gas-vs-diesel-for-towing-a-fifth-wheel/
Source: The Fast Lane Truck