The actions of your horse say that he is very scared of being out on the trails. So, you have to work on making him feel ok about it.
One common way of getting a horse to accept something that scares him is the "approach and retreat" method. This works becuase you ask the horse to go toward the scary thing, and just before the horse gets to his "cant' tolerate a second more" point, you turn him away from it and retreat, allowing him a break in the emotional pressure. Then, after a bit, you ask him forward, a tiny bit further, and again allow him to retreat (at YOUR choosing, and BEFORE he can't handle another second).
Once the hrose knows that he won't have to go forward endlessley , without a break, then he will become more confident about the whole affair.