Do you need a 3/4-ton or 1-ton truck for a fifth wheel?

For fifth wheels, payload is usually the deciding number. Not advertised tow rating. A fifth wheel puts a lot of weight in the bed. That pin weight counts against the truck's payload along with passengers, hitch, tools, fuel, and cargo. Many 3/4-ton diesel trucks have less payload than buyers expect because the diesel engine and higher trim options are heavy. Check the actual door-jamb payload sticker on the truck you are buying. Do not rely only on online charts. Then estimate loaded pin weight, not empty brochure weight. A camper that looks reasonable on paper can push a 2500 over payload once it is loaded. A 1-ton single rear wheel truck often gives more margin without going full dually. A dually gives more stability and rear tire capacity for heavier fifth wheels. If the numbers are close, buy more truck. It is cheaper than regretting the setup later.