Thanks, BorntoRun, I will study those!
And thanks to all for the tips.
churumbeque and greentree, good advice. I will ask someone to come along.
I know the trails pretty well (I've ridden them with the horse I used to lease at the same barn), and walking a bit of them in hand is a good idea.
Nancy, thanks — good idea about having someone take me through the proper reactions for all kinds of spooks.
I think I'll start walking him on the trails like some of you suggested. I'm very comfortable on the ground with him even when he's alarmed, and he listens even when he's frightened, so I think we can start with that while we continue our arena work.
Thanks again! :)
"...and may your life be filled with good horses." — Buck Brannaman