My horse had a lot of anxiety about backing off my trailer, he would always want to turn around and walk straight off, so I taught him to back out of the trailer by REPEATEDLY practicing backing on the ground.
I would walk him forward btween 2 posts, my cross tie area, and then I would use my crop, "as an extention of my arm" and help guide his body backward, as if we were backing off the trailer. I would touch him in various places with my crop to get those body parts to move, AND, PRACTICE saying WHOA, or OVER when I needed his feet or body, to change direction, or to stop moving, so he wouldn't fly off the trailer and fall.
And, so I could TIME his steps, and control his movement.
I practiced the same "Cues" every time and when it came time for him to back off the trailer, he just did what we had done btween the cross ties.
I also incorporated the word "Step" when he would have to step off the back, so when he hears that "Cue" he knows the next step is downward onto the grass.
I also always try to position my trailer on to nice level ground so as to make the step down easier, not some Big Terrifying step off into the "Great Abyss".
I just make it as easy as possible for him.
Since he's a quick learner, he understands that it's ok.
He is still sometimes anxious, but I ALWAYS praise him and reassure him when we finish that last step onto the ground.
Plus I reward him with a hug and a pat and treat, thereby turning his negative into a positive experience

.
It took practice, but he is so AWESOME and TRUSTING about it now, and he trusts that I won't put him in a dangerous position.
Worked well for me, give it a try. Redboy
PS. As John Lyons says, "Horses are "Condition Response" animals.
If you repeatedly set up the SAME CONDITION, you will get the SAME RESPONSE every time".
Good Luck, RB
