Join Date: Nov 2016
Location: Lansing, Michigan
Are you planning on hauling him with the divider open or shut? If the divider is open, yes he needs to be tied - you don't want him turning around willy-nilly in a two horse slant unless the divider is taken out and there is no rear tack room. In my opinion, that space is just too tight for him to navigate in a moving vehicle, and you wouldn't want the trailer to jolt at the wrong time and put him on the floor.
If the divider is closed, I think it's up to you on whether or not you tie him. I tied my horses during a 10-hour ride, and allowed them full mobility of their necks, but I wanted them to have a lead on in-case of emergency, especially on my hard-to-catch mare.
I'm sure you know this, but absolutely no elastic/bungee trailer ties - they are dangerous in the case of an emergency and can hurt (and take out eyes) of humans and horses. Also, make sure to tie a twine loop to your horses halter ring, and then attach a nylon trailer tie - NOT the other way around with the twine attached to the trailer - same concern of the twine breaking and sending a trailer tie towards you or your horses face.
I would consider stopping and unloading for the night someplace with a 20 hour drive - my longest trailer ride with my horses was 12 hours, and that was when my horse was much younger and we had a roomy trailer. I would especially consider stopping if your horse doesn't readily eat and drink in a trailer - colic is a concern of mine because my horse will barely pick hay in a trailer (even the best, greenest, freshest hay) and won't drink either. If you have concerns of him not getting back on the trailer, well that comes down to training and patience.
Good luck - and I hope your horse adapts to the heat of Alabama well!
He's Ultimately Fine - Toofine - 1998 Half Arabian
Wilhelmina - Minnie - 2013 Morgan