Just the facts Ma'am.
I have hauled a good size 2 horse with big tackroom with both an Expedition 2010(V8, 5.4L, 3.73, EL=wheelbase of 1.44 inches) and prior to that a '05 F150 ( V8, 5.4L, 3.55, 4door, 5.5 ft bed)
Both hauled just fine in all conditions. Gas mileage was not good, but we were more concerned with safety.
That being said, after 87k miles of Moderate use on the F150 ( Long trips out of State 4-5 times a year) I had to rebuild the rear differential (the gear box, a 3.55 ratio) costing $2500 in 2011. But I found this acceptable, because it would have cost me more in gas for everyday driving to/from work with anything bigger( F250, 3.73, etc)
Hope that helps someone.