Maybe if you gave us more details about the fifth wheel (GVWR,empty weight, pin weight, weight loaded for camping, etc) and more about the truck you are considering (same type info plus axle weight ratings, year, brand, body style, GVWR, RAWR, etc)) we could have a basis for helping you. I have no info whether your loaded trailer is 12K or 17K lbs. Without more info, my general opinion is a NEW 3500 SRW can generally do pretty well up to about 13-14K. Above 14K I would be staying with DRW. It may work out to be different in your case, but you can only know if you work the numbers. Good luck with your decision.