Honestly? I wouldn't tie him to it. I'd work around the trailer plenty, quick tie him when you are saddling and have to tie him there, but I wouldn't leave him tied hard. Tie welds on trailers can break, and he could go down, cut himself up or bang up the trailer. He may get better over time... but if he has a wreck where he breaks the trailer, he will get worse.
Boy can they. At the endurance ride, DIL had stud double tied to the trailer, so that if he decided to leave, he'd have to break two ropes, not one. He sat back and broke the trailer. Trotted through the entire camp, then stopped and waited for her to get to him, went back to the trailer gentle as a lamb. He was not frightened of the trailer or being tied, just being an a$$. I agree, I wouldn't tie any horse afraid of being tied to a trailer, to much chance of serious injury.