:::: UPDATE ::::
Misae is backing out of the trailer like a champ now! Thank you so much! Took about 10 tries before she stopped trying to turn around, and then I was able to lead her out backward without help. I did that another dozen times or so until she stopped trembling about the whole deal and was being confident about stepping out. No flipping. She sat down a couple times in the beginning (the very first try she did manage to somehow turn around) but once she got that first back hoof solid on the ground, she was ok. (If she didn't get a solid footing she would try to bounce back in, as you said, but she got better and better with each try).
Thanks so much!