Looking for my first 3.5T horsebox. Wanting advice on safety features. Many boxes say emergency exit and have wide back door or double van doors. I am confused about what I should have between the grooms area and the horse area for safety. Some seem to be fixed panels, others with wide door in middle and others have a collapsible breast bar. What would people recommend? What is best for a 14.2 pony to lean on? I do realise that backward facing means they will rely on their rear ends if stop suddenly. My budget is around £12K. Many thanks.