I see this thread is still running.
I towed a 5000-ish pound 2006 (purchased early in 2005, of course) Roo 23SS at max capacity with my 2002 full frame, 4WD (RWD) 4.0 V6 Explorer for two seasons. 5500 pound max tow rating This Explorer was purchased to tow a 3500 pound popup which it did effortlessly. "I could have had a V8" but the 7200 pound rated V8 seemed excessive for the popup and we never thought we'd buy a hybrid two years later. Never comfortable flogging the V6 up hills and against the wind so it was replaced in 2007 with a full frame 5.4 V8 Expedition with a 9000 pound maximum tow rating. Ran this truck for 180,000 miles until the '17 Expedition. Smallest towing engine yet at 3.5 liters. Even my wife's Subaru has 3.6. :)
The Explorer remained in the family another 10 years as my daughter's car. Typical, minor problems with the truck during that time but none related to the drive train which I assume would have been the the result of towing the bigger camper very near max rating.
-- Chuck