Our daughter is like yours. She started young.. After the first month, she said, ok, now tell me about tampons, I hate pads.
And so I purchased some to the slims by Tampax. I had her practice pushing the tube.
Then I stood outside of the bathroom door and told her to sit on the potty and to reach down and find the place where her urine comes out.
Then I told her right behind that is were the blood comes out. That is where she needed to insert.
I also told her once it is inside, she should not feel it and it would not get lost in there. After just a few minutes, she said "I think I got it"..
She was so happy and proud to be able to do this..
Have her practice before she goes to camp, even if she is not having her period.. Make sure it does not bother her.