Seems pretty simple to me. We're talking about essentially the same rear end, same motor, and same tranny used in cars like Panthers (Crown Vics, Grand Monkeys, Town Cars) that tow stuff all day long, all over the country, day in and day out, and nobody so much as blinks at that ... and those cars have the Lo-Po 5.0 and about 1,000 extra pounds of body weight to haul around. As long as you don't go trying to cruise in OD on the highway, or try to race someone while you've got a trailer behind you, you will NOT fry your tranny. Ditto for someone running a T-5 - just keep it in 4th, if you're that worried about it, and you'll be fine.
Sure, your gas mileage will suck, and it probably wouldn't be a bad idea to change out your fluids when you arrive at your desination, but light to mild towing with a 5.0 Fox is NOT a death sentence for the car's drivetrain. That's just plain silly. Just because it looks weird and out of place doesn't necessarily mean the car isn't capable of doing it.
If you need Ford's official say-so on the matter, consult your owner's manual ... if anyone out there still has one from their car, that is. There's usually a maximum tow capacity listed in there. Jeez, even a Geo Metro has a listed tow capacity.
Myself, I'm considering the option of buying one of those little cheap-o trailers from Harbor Freight sometime later this year if/when I get a chance to move back to the Midwest, mounting a U-Haul or Reese trailer hitch on the 'Stang, and hauling my excess oversized goodies on that almost 1,500 miles. Of course, it's not like I'll be hauling appliances or anything over 100 lbs. - mostly just my car-related crap like my X-pipe and tools - so I'm thinking it'd be 1,000 lbs. at most, total ... which, again, is nothing more than a Panther has to haul around every day on its own WITHOUT a trailer attached.
FWIW, as soon as I arrive at my destination, though, I fully intend to ditch the hitch and sell that and the trailer to recoup some of my moving expenses.