GVWR 15,500. Your number is empty weight from the factory.
I had a Montana High Country mid bunk, around 14000 empty and gvwr 16500, I went with a dually crew cab cummins aisin.
There are lots of different variations of a 2021 Ram 2500 turbo diesel. 4x4, 2x4, standard cab, crew cab, different bed lengths and different equipment packages. All of them have different towing capabilities.
You need to find the sticker on the driver door jamb or door side with the payload capabilities. That will show you how much pin weight you can handle, and you have to deduct passengers and things in the bed of the truck like the fifth wheel hitch from that number. Plus it's good to have a safety factor. The advertised pin weight of your fifth wheel trailer will be low, I guarantee it will be more than advertised, especially when you load it up.
A lot of people I see on the road are doing it, I decided not to do it for reasons of safety. I traded in a 2015 duramax 2500 for the ram dually to pull my fifth wheel.
