. . . I cannot think about what I would put in the trailer that would add 1,000, but maybe I am wrong since I am new at this. Am I wrong? Please advice.
The coaches you mention will carry 30 gallons of water. that is 250 pounds right there. Waste water could be twice that much on occasion. I am not sure whether Keystone rates their trailers with batteries and full propane bottles or not but those items could weigh another 200 pounds or more, depending on what batteries and propane canisters you choose.
Please don't misunderstand. I am not saying the combination is unsafe or unworkable. I am just saying I would prefer a little more weight margin.
My 2012 Passport is rated with full propane bottles and full fresh water tank, but empty black and grey tanks, according to both the sticker and manual.
I was told yesterday by a Keystone rep that the weights are calculated using empty propane tanks. He (Cougar Rep) said that each trailer is weighed, but the hitch weight is a mathmatical calculation that is accurate to within 40-50 lbs.
I pull a similar rig as you have. I have the Passport 3050 w/f150 screw 5.4L. I weighed my truck empty at the scales. Then with the loaded rig including people. I can tell you towing capacity is not your limiting factor. With a half ton truck, the key from what I have experienced and learned is the axle weights. Do not exceed those. I do not carry heavy loads in the truck bed while towing. I put as much as I can in the camper. Heavy items like my generators go right above the axle in the camper. I also have a bike carrier on the rear of the camper to offset some weight from the LP tanks and battery. The net effect is a balanced camper and truck with a bout 12% weight on the tongue. We just towed my truck with DW, two kids and dog in the cab. Nothing in the bed. All gear in the camper. Axle weights were 3650 lb front and rear. That gave me 100 lbs cushion on the front and 200 lbs on the rear. My extra towing capacity was over 2200 lbs. so watch the axle weights. Towing capacity is not your limiting factor.
I think you will be great with a passport. It's a great camper and we love ours.