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.
Trailers just aren't strong enough... and too many things to cut themselves on.
No, I don't think he'll ground tie. But good idea about the panels, and working with him just being close to the trailer without tieing him there for awhile.
Your reasons for not tieing him are exactly why I haven't done it much. Mack has reinforced welded my tie rings on the trailer, I don't think they would break, but it's the injuries to himself that worry me.
Becky