When you go to do your step up, make sure your whole foot is on the bench. You want to focus on those leg muscles to work the back of the legs and the top of the thigh. This exercise is not about reps, it is about time. When you build up that strength, you can add more risers to make the step even higher.
Another exercise that would be good to do to help you on that hike is the side to sides with a bosu. This helps with balance since you will be walking on many uneven surfaces. You also want to do some forward and backward steps. Making sure, you are doing these moves intentional because it is going to help the feet, the ankles, the knee and the thigh.
If you strengthen the heart and lunges with cardio you will enjoy your hike. All of these very important factors are a great combination to a healthy, happy hike!