How "secure" do you feel on your horse? How balanced are you, as a rider? If the horse stumbles, how do you react? Do you rely on your saddle/stirrups or reins for "balance" going up or down hills?
Do you have independent hands, or do you "grasp" the reins (and horse's mouth) to rely on them for balance if there is a trip or stumble?
How well does your horse listen to you when you're in a "tight spot?" Does she get nervous and hurried if the footing is bad, or will she pick her way through tricky spots?
Just some things to consider.
A horse doesn't want to fall off a cliff any more than you do, but when it's carrying a rider that rider can either be a help or a hinderance to the horse's balance.
Is there anyone you know who knows the trails, and has a seasoned trail horse, who might be willing to go with you on that trail or at least tell you what to watch out for?