I have a 2005 F350 LB CC 4x4, been towing a 5th wheel an flat bed trailers for over 11 years with this truck an never looked back an yes it a 6.0 with no problems. I did however bullet proof it at 250k miles, engine was clean as a pin inside with that amount of mileage...
I am not one to hot rod my trucks, I drive them an average of 60 to 65mph when pulling a loaded trailer an use lower gears when climbing mountain pass out here in the west... I seem to pass all those hot dogs that race up the top of the mountain passes an have to stop an get fuel while I just drive slow an steady :)
I believe the newer Ford 350 an 450 are a great investments, I have driven an owned all types of ford products including Semi tractors for over 50 years, if you treat them well they will treat you well ...
Safe Travels