OK a little research shows that you have a 2014 2500HD, what we do not know is it a short bed or long bed, if it is a short bed and you plan on an auto slider hitch it adds an extra 100 pounds or so to the truck, which subtracts from the amount of pin weight you can handle along with everything else you place in the bed.
Generally speaking 250/2500 are good for 5th wheels around 12,000 to 14,000. Above that you will be under the manufacturers published numbers. Over that and you run into RGAWR which is a number you do not want to exceed without update rear wheels and tires to something like 19.5 rims and tires.
In today's world of heavy diesel pickups, I find it hard to understand why people still buy 250/2500 trucks and then want to tow larger 5th wheels. My 2015 RAM 3500 SB CC 4x4 has a GVWR of 11.700 and RGAWR of 7K. The LB model has a 12,300 GVWR. The 2500 has a 6500 RGAWR and 10,000 GVWR. Many tow over the GVWR, however going over RGAWR is not advised. Chris