We use both a 2 horse rear load trailer and a "combo" trailer for hauling our Longhorns as well as horses (but not at same time). The 2 horse trailer can haul ONE adult cow or bull...works fine; or, to haul 2 calves.
The Combo trailer has center divider and we can haull 1 or 2 in each section, depending on their size. Can haul one cow and her nursing calf in each section.
Have used this system hauling Lo0nghorns 4-6 hours to a show with no problems, as well as hauling one or 2 same distance. Helps to give them a flake or two of hau to munch on while they are traveling--keeps their mind off other things.