With exactly ZERO information about the style of fifth wheel you're looking for (rear living, bunkhouse, etc), how can anyone answer this question??
We can't.....which leads to all the different opinions/speculations especially when a 1/2 ton truck is mentioned. Some folks are flat clueless of what this truck is capable of in terms of payload. No its certainly not a 3/4 ton truck with a full floater 6000-6500 RAWR.
The Titan gas or diesel will have about the same in the bed payload as both have the same 4900 RAWR to work with and both rear axles will scale about the same just like the bigger gazz/diesel trucks.
To be on the safe side just stay under the trucks 4900 RAWR (axle/brakes/tires/wheels and rear spring pack ratings).