I'm not exactly sure what shadow boxing is. So I can't make a guess about shadow shooting. But I can say that unless you can't hit the broad side of a barn, marksmanship is a minor concern at copper school.
Of all the components of copper school, I always felt that PT upper body strength (pull ups) was the biggest challenge. I was a good runner and a good academic student (books). But I was never one of those playground/monkey bars monsters who could do a gazillion pullups.
Run. Do pushups. Get good at pullups. Shoot a little if you like. Hone your note taking skills. Hone your listening and observation skills. Hone your English language speaking, reading and writing skills. And if you don't already speak Spanish and/or one of the Asian languages, hone up on at least Spanish.