An Expedition is basically an F150 with a real soft suspension. It should be capable of towing a 4000 to 5000 lb trailer (fully loaded weight also known as Gross Vehicle Weight Rating, or GVWR, which is found on a sticker on the front LH side of the trailer along with tire sizes, pressures, etc.
As others have noted, don't buy a motorized RV (motorhome) as it is lots more insurance, maintenance costs, registration costs, limits your travel after you get to a campground and set up, etc.
If the Expedition is high mileage, heavily rusted, etc and you don't want to be pulling a trailer with it, consider a F150 or similar pickup truck (or something with decent tow ratings such as a Nissan 3500 passenger model van) as a family hauler upgrade. (stay away from the typical soccer mom SUV models that won't tow much, (you can add a topper to the bed to carry stuff like chairs, grill, or the groceries, out of the weather)
Charles