Newbie Question on towing with my Ford Expedition

That's quite a load. You will be way over your limits with all that plus your weight and other cargo in the Expediton. Better buy a truck with a bit more power. I had an Expedition with the 5.4L. It struggled to pull my trailer and ate gas like a pirate drinks rum. I have a diesel now. Great mileage and I don't know I have a trailer back there. That 4.6L would be good for a pop up or something. I'm not sure you will make it up much of a mountain without overheating either.