Air Force, Navy, and Army prep academies have teams, though I don't know who they play. It is a one-year thing, which would probably fit BYU pretty well. The catch is that since it is an extension of high school, they are free to go anywhere after that year, and at least one time BYU had a transfer from the Air Force prep school.

There are also the prep academies that are basketball powers, such as Farragut and Oak Hill. However, I think they are more traditional 4-year high schools.

Go Cougs!!!!