The pin weight is listed as 1,420 lbs or there about.Add the truck's weight, passenger weight, cargo weight, fuel weight plus the weight of the hitch and I bet you are over the gross carry weight for your RAM. You need to read the mfg's plate on the driver's door sill for exact numbers. Remember, not one of us goes out with a coach weighing just the empty weight. You have food, clothes, bedding, TV set(s), water, propane, etc.
I know I will get castigated but it is pretty much a given that 1/2 ton trucks are not suitable for towing 5th wheel RVs. Many people do it. You did not tell us the year of your truck. Many new trucks far exceed the towing capacity of even two or three years ago. Many say they can tow with a 1/2 ton but the braking does become an issue.