Not only will you have no trouble pulling that TT with a 5.0 you will probably get the same mileage as an EB towing. A little less torque and HP won't make that much of a difference as the trailer will probably load out around 6K# mas y menos. I get almost the same mileage as an EB with my 06 5.4L non towing and the same or better towing our 5K# TT.
From everything I've read the 5.0 is a step up from the 5.4 which is without a doubt one of the best motors Ford ever produced. EB's remain overpriced and if buying new I would not hesitate to get the 5.0. :C