First, what are you hauling in? Is it a reliable truck and trailer in good, serviceable condition? If so, you can DIY. If not, ship them.
Second, what are you shipping? Old, retired horses or young, healthy ones? Old and retired, ship them. Youngsters, haul them.
How far are you going? I did quick Maps search and it’s about 14 hours from Mason City to Jackson. That’s a long, one day haul but a one day haul. You can even go a bit farther with young horses and two drivers. On long hauls (East TN to El Reno, OK; about the same distance) we’ve done it non-stop multiple times. It’s about our ultimate daily haul distance. We do NOT ever unload on the road unless we are stopping for the night. And NEVER unload at a highway rest area. In a lot of place it’s unlawful. And if you have re-loading issue…you might really SOL.
We stop every two hours for a bathroom break and that gives the horses a short break, too. We do a lunch stop and, on longer hauls, a dinner stop. In more than 15 years of multi-day hauling I’ve never had any of our horses drink on the road. They just don’t do it. I don’t bother to offer anymore. Going all day without water in normal temperatures will not overly stress a healthy horse. They do have a hay bag to munch on.
Breaking a trip at a “horse motel” after a few hours is not a bad idea but is not actually a necessary thing, either.
Good luck on your run! 
G.