After the 12 mile hike
CrossFit is a general physical preparedness program. That means the aim is to get you ready for anything. We train with intensity because it is the key variable associated with favorable adaptations. In other words if all you ever do is long distance slowly you will probably have trouble completing Fran, but if you do CrossFit you will probably have no problem hiking 12 miles.
As many rounds and reps as possible in ten minutes of:
55kg Squat clean, 6 reps