I used clicker to get my older boy to load in the trailer. The key for him was to break it down into very small pieces. Without clicker, I got him to where he would load, but someone would have to lock me in the trailer so I could get the divider fastened. One trainer insisted he would hold the door shut and it would be fine. Strider knew the difference and knocked him on his butt shooting backwards out of the trailer. Small enough pieces for Strider meant an extremely small weight shift on my part. Not moving my feet, just shifting my weight. Then me just moving one foot. When I got him so that I could walk around inside the trailer without him shooting out, I touched the divider. Then I progressed to moving it a hair. Eventually I was able to load him by myself. The key was to break it down into small enough pieces for my horse. I learned from books.