dodge v6

30 lb propane cylinders weigh 55 lbs each counting the tank when full. 20 lb propane cylinders weigh about 38 lb each when full. Batteries could weigh 60 to over a hundred pounds each. Each 10 gallons of water in the freshwater tank is about 83.4 lb. 40 gallons of freshwater is 335 lbs. Don't forget to include those in the gross vehicle weight of the trailer. If waiting until getting home before dumping the black tank, keep in mind the shifting of water from the fresh water tank to the black water tank could create issues with the tongue weight. I normally have a lighter tongue on the way home and have to compensate by moving stuff in the trailer to the front of the trailer.