total weight and pin weight for a confortable tow

With any of the newer Diesels, towing isn't the problem as any of they will just about tow a house. What you need to worry about in the Pin Weight as that is the Down Fall of 250/2500 and 350/3500 SRW series TVs. So you need to load everything in the TV (passengers, pets, cargo, hitch, and full tank of fuel) as you would for a trip, weigh it then subtract that number from the TV GVWR (gross) as shown on the driver's door pillar. That number that's left over is the pin weight you can carry.