Joe4d for your horse that might work. For mine absolutely not. I don't want to travel uncomfortably so why would I ask my equine partner to do so? Also the emotional trauma that would cause is not worth it. My horse has the capabilities to travel in any type of trailer with no mishap and little to no resistance. But as an owner that cares for my animal I will make him comfortable.
Blue eyed pony that's how my gelding is. I make sure to take every turn with as little jarring that is possible. He has actually gone down in the trailer once, hasn't done it in almost a year though but did knick himself. But you noticed that giving him the option of how he wanted to stand made a difference with the divider being tied off?
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Monty needs the room to spread his hind legs. In a normal-sized bay he doesn't feel like he has it. In a super-wide bay, or with the divider tied across, he ALWAYS travels dead straight [and rock solid!] but with his hind legs spread really wide.
Tying the divider across is the best way for me to trailer my lad but isn't always possible [don't own my own trailer so usually have to travel with company]... and you always know he's not happy when you don't have it tied across! He's getting better now but needs extremely careful driving in a normal-sized bay [literally CRAWLING around corners, very slow acceleration, avoiding bumpy roads, the works]. In a super-wide bay or with the divider tied across he's rock solid no matter what.
Monty has NEVER been more solid than he was the one time I trailered him in a horse-and-a-half-sized single. It was actually for sale for a very reasonable price but having two horses, it just wasn't going to fit my needs.
The other thing is, my lad travels [and loads!] better in a wooden trailer than he does in a metal one.
Joe4d, do YOU have a scrambler? Do you have experience with them? Granted OP's choice of words was not great, but scrambling is something that is damaging to the trailer, not to mention very dangerous for the poor horse! If it CAN be prevented, it SHOULD be prevented, and if you have a horse that scrambles, you do everything in your power to help that horse out. Yes, careful driving helps, but some horses [like mine, and he's not even that bad!!] are SO sensitive that a bump in the road is all it takes to set them off. Some just scramble no matter what you do driving-wise. Some scramble on the straight at a steady speed.
MY horse scrambles because of a traumatic experience at the hands of a transport driver. He was put in a far-too-small bay, which to start with didn't help, and then evidently not driven well [as according to previous owner too-small bays never bothered him in and of themselves]. He went down twice in the truck, took skin off a stifle and twisted a knee so bad he went dog lame and the whole leg swelled to 3x its normal size. Even now he STILL has an enlarged pastern.
...AND there's something off in his hind end...
...AND he suffered constant muscular pain for MONTHS afterwards. Even now his loins sometimes get sore, nearly two years after the fact.
It took me MONTHS to get him to set foot in a trailer again, longer to get him to actually travel in one, and, TWO YEARS after his bad experience, this previously fantastic traveller is still a mild scrambler. Since I have had him he has been towed with the best of care, the most patient and careful drivers, and only ever in extended-width bays or with the divider tied across. He has been trailered on a particular brand of trailer that is specifically designed to stop them climbing the walls. I have tried him on 4 different trailers, with and without company, tied and untied, both sides of the trailer, divider tied across, super-super-large bay, you name it I have tried it with him. So I know that scramblers have psychological issues regarding trailering - usually caused by poor driving, not necessarily the fault of the owner who has to actually deal with the issue.
The ONLY thing I haven't done with my boy is try him in transport boots, and I haven't done that because I've read that it can make scramblers worse. Especially if the boots slip down. I bandage his hinds to keep them clean [3 white socks is a curse come show day!] but never use boots.
With scramblers it's just a matter of finding out the way THEY are most comfortable being trailered, and it's incredibly individual. Some horses need not to be tied, my boy can't cope without that "safety blanket". Some horses need to travel at an angle, some need to travel straight. Some need more room for their legs, others need to be squished into a bay that's technically too small because they feel supported that way. Some don't care what side of the trailer they're on, and others freak out on one side and are fine on the other. It's all incredibly individual, and it's all about what works for YOUR horse.