The front to rear weight distribution is important when trying to answer questions like this. For example:
My 2009 F-350 4X4 V-10 Gasser has a 5200 lb. front axle rating and a 7000 lb. rear axle rating. The GVW rating is 11000 lbs.
With the camper (8' S&S bitteroot hardside)loaded with my gear and full water tank it rolls across the scales 4900 lb front, 6080 lb. rear and a total weight of 10980 lb.
You can see that I am 300 lbs under the axle rating for the front and 920 lbs under the axle rating for the rear due to the center of gravity of the camper and having that CG just in front of the rear axle. My front to rear balance is biased more to the front than most camper truck rigs. It handles very well like this. Having a diesel in my particular situation would have produced an overloaded front axle.
Each rig will have a different result for front to rear balance based on truck camper combined CG.