I couldn't find a 2002 TourMaster brochure, 2000 was the closest year of TourMaster listed on the Gulf Stream website. The 2000 only had a receiver capable of towing a 5000 lb load, a 2004 Expedition weighs in at 5300 lbs. You can't modify the tow rating, you must stay under it.
Gulf Stream brochures
Modifying a 12 year old vehicle for towing costs as much as modifying a newer vehicle that might be a better investment.
Because of the size of the Ford and the age, I'd really suggest finding a vehicle that would be a better fit for use as a toad.