Hi Rex and welcome to the forum. Is the 7000 loaded or unloaded weight? Does the expedition have the towing package and what is the rear axle ratio? Your owner manual should have the tow rating listed. year model would help also.
There is safe, and there is pleasant. If the vehicle is a 'half-ton' truck, then 7000 pounds may be near or even over the limit for safe towing. The 5.4L gas engine may pull ok on the flats, but probably will not be pleasant going up hills.