Are there any camps where you can have pre-military training?

Answer 1

The Seventh Day Adventist Church ran a version of military basic training because those who were later drafted came into the service as conscientuous objectors who would not be carry firearms. To prevent their armed companions in the military from picking on them during basic training, they sent their young men through training before conscription. I doubt that they have it now, since no one is getting drafted, but you can always check with one of their local churches.

Answer 2

Depends on what you mean.

There are military high schools.

There is JROTC in a lot of regular high schools.

There are summer camps associated with JROTC.

If you are looking at West Point, there is the West Point Prep School.