According to NADA guide, that 6600 lb figure is an unloaded weight. When that trailer is ready to hit the road on a camping trip, it could easily weigh 900 - 1000 lbs more. That would put trailer weight around 7500 lbs., with tongue weight in the area of 950 lbs. The weight of your WD hitch would add another 75 - 100 lbs. The number that may bite you, is your available payload. You will run out of payload and exceed GVWR, before you get close to that 10,000 lb hitch rating.
On your drivers door jamb, should be a tire and loading sticker. It will show a max weight number, for occupants and cargo. That's your truck's capacity to carry any aftermarket accessories (bed cap, bed liner, step bars, etc), driver and passengers, cargo in truck bed, WD hitch, and trailer tongue weight, all combined.
Not all Ram 1500's are created equal. They each have their own payload number. I've seen some as low as 1200 lbs, and some as high as 1900. You may or may not be over on your ratings.
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Example:
Say your sticker says max passenger / cargo is 1500 lbs. You add a 200 lb bed cap and put 100 lbs of tools in the bed. You now have 1200 lbs of payload available.
Your family gets in the truck, with combined weight of 450 lbs. Now, you're down to 800 lbs available payload.
If your trailer has loaded weights of 7500 lbs, with 950 tongue weight, and your WD hitch weighs 100 lbs. You'd be 250 lbs over on payload and GVWR.
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