If I only have two horses to haul, I love using my Ford 3/4 ton conversion van. It's an absolute dream for comfort, power, cozy (if rustic) camping. It is not rated for enough weight to add the third horse. We hauled one horse over to the Dust Devils ride in a snow storm with no trouble at all.
We did, however, have a truly nasty accident pulling a 26 ft travel trailer with a 15 passenger Dodge van - you know those ones that want to roll? We had hauled this rig all over, even from Oregon to Mexico and back, but going about 50 miles an hour, on a dry straight smooth stretch of interstate, with all the stabalizing and safety equipment working and in place, the trailer started to sway, we did a 180 and rolled both the van and the trailer. Both rigs were totaled, but none of us were hurt, including our son and daughter who were in their wheelchairs, attached with tie-downs to the van floor. I am sure it was an EMT's worst nightmare!