I ship down to Thermal every year, which is a 22-24 hour haul, with 4 horses in my 4H slant load trailer. One way I overnight halfway and the other way I go straight through. I do all of the driving on the 12/12, and my husband is with me for the 24 and does more of the driving (and thankfully always does the 10pm - 4am part). Horses don’t seem to care either way, and show up at the end of the 2x12 or 1x24 trip looking about the same. I hang water buckets and stop every few hours (for gas, food, etc.) and the horses have hay in front of them the whole time. My personal preference is the layover at the midway point, but honestly, for a one time trip? I really don’t think it matters much either way.
When we moved from Virginia to Florida, the horses went with a very good professional shipper a few days before we left. It was the right decision. I drove the trailer filled with many of our belongings. After packing, closing the house sale, and vacating the house, I was in no shape to drive horses. I drove about 7 hours, and we then went to a dog friendly motel for some sleep. The horses arrived in about 14 hours. They looked better than we looked after their night in the spacious air ride commercial rig. My friend cared for them for a few days, until we were fully moved in.