Frank,
We pull a Reflection 5th wheel with a 6.5' 2500HD without a slider and have no problems whatsoever (Andersen Ultimate). One thing that we discovered and I would caution you about is this: with a diesel 2500, you will run out of payload capacity for pin weight on the rear axle and tires LONG before you reach the max towing capacity of the truck. Fifth wheels typically put 23 - 25% of their GVWR (not empty or curb weight) on the pin when loaded. With your added fuel capacity and a 200+ lb. PullRite auto-slider, you may be surprised at what you have left over for pin weight. For example, our truck scales at 7,520# (3,080 of that on the rear axle) with our 36 gallons of fuel, a driver, and the 37 lb. Andersen hitch. That leaves me with 3,120 to spare on the axle (3,310 on the tires) before hitching up. The last pin weight on the trailer across the scales was 3,200 lbs., putting us just 110 lbs. below the rear axle ratings (but 560 lbs. over on the truck as a whole).
That said, I'm extremely happy with the Andersen Ultimate (which saves me over 150 lbs. in weight and is easy to remove) and a Demco Glide Ride pin box. Bilstein 4600 shocks and Timbrens round out the truck package.
Rob