[rhagfo]

Well as Danny (Sourdough) pointed you have a very small payload (1,440#) for a 40' 5th wheel.

I would strongly, heading to the scales before you put anything besides two full propane tanks and necessary batteries. You only appear to have a 13,820# GVWR on that 5th wheel. You might check the Payload/VIN sticker on the trailer as the 13,820# number is the sum of the base weight and payload weight. That way you could also get a true dry pin weight.
The real concern is that any weight above the 12,380# shipping weight will reduce the 1,440# carrying capacity.
We full time which is like packing for a long trip, in a 32' 5th wheel, and we exceed our 2,106# carrying Capacity which included 45 gallons of fresh water, and 60# of propane.
The dry pin of 1,820# likely will not exceed 2,800# which is what our pin on our 32' 5er is, which we carried on your old 2001 Ram 2500 without air bags.
Good luck on your trip.