Re: CrossFit doesnt work...
I'd also offer that the age group you're working with might be a challenge. I was the Command Fitness Leader at a large Navy school for a couple of years. While we had a pretty low number of PRT/BCA failures, the VAST majority were in the 17-19 and 20-24 age groups. There are a few exceptions in any group, but I see the same thing at my current command. The level of commitment, goal focus and willingness to endure suck just isn't there, IMHO.
I think you'd get a more representative sampling if you opened up the age groups and (as others have said) actually did CF, vice sort of CF.