I'm being a thickie, and still don't understand the problem. I have a two horse straight load. There are two tie rings at the front, on the wall to the outer side of the horses head, about 6 inches higher than the height of a 16 hand horse's head. I use the quick release trailer ties and take off the lead rope.
So if I have a horse in that is likely to have a go at it's travelling companion, I adjust the tie length, and clip it from the head collar to the tie ring. It's long enough for the horse to eat from the hay net in front, and short enough to prevent him from getting head under breast bar, or annoy neighbour. The safe release tie doesn't have any loose ends for him to grab, and it's not floppy enough for him to grab and eat.