Maybe on Harley, but it won't be to avoid tying him to the trailer.
My son is here and we are discussing letting horses graze with the lead rope dragging. I know he hobbles his horses, and asked him if you could hobble one to let them graze, I've seen that done. He is telling me he uses hobbles to minimize movement on a young horses when tied up. He also told me he knows how to hobble one that won't stand for mounting. He can hobble one with the tail end reaching the saddle, mount the horse then pull the tail and it all comes off. I thought that was cool:)
He says the first time you hobble one put them in the middle of a big area, and keep an eye on them. He says he has never seen one fall. The ones he has seen, tried to walk around, then would hop around a bit then just stop. He does not leave them long loose with hobbles. He doesn not want them to learn they can walk around with them on. They are to minimize movement while the horse is tied up.
Becky
Someone recommended hobbling on Tiffney's mare, the one who absolutely freaks out if she gets hung up or feels claustrophobic when tied. A cowboy type said... "hobble her and let her fight herself until she gets tired." I talked her out of it. Her mare is so violent about that kind of thing, it seems a very dangerous lesson for her, one where she won't stop fighting until she can't fight any more, might likely throw herself down and/or get hurt, and I am not sure she wouldn't become even more phobic. I just thought for her it would be too dangerous. If I put hobbles on Bay, I'm sure he'd just stand there. Big difference.
One of my cousin's hobbles her horses when on break at a trail ride. She also has a short length of rope with a loop on one end and a snap on the other. You run the hobbles through the loop, then put the hobbles on the horse, then hook the snap end of the rope to the halter ring. They can graze, but can't raise their head above knee level. It eliminates the problem with them learning to run off with the hobbles on. I've never seen anyone else do it that way though.