I know this is way off topic and unrelated to the OP but if you do not mind me asking, where did you graduate? My curiosity is a result of one of your comments to one of my posts a while back. Again sorry for being irrelevant to your post.

Honestly i would leave a note on his stand with your phone number and have him call you. Thats not being an ass about it at all in my opinion. You are concerned for your son's safety as you should be. He may not know that he is encroaching on your property.

i actually have the SAME exact thing going on at my family property so i will be interested to hear this outcome.
Guy put a boxstand literally 15 feet from one of my fields. He can make the argument that he is hunting the opposite direction, but i know deer do not cross there because it is a flooded pipeline. They use my field to cross. Something will happen soon. Unlike you, i have no camp to worry about haha

I have had the same problems in the past, seems like everyboby loves the property line. Seeing how its public property I would put a couple POSTED signs up on the property line, and I'd leave him a note that he is shooting directly at your stand and the slough you duck hunt. Nothing wrong with being concerned for your safety and the safety of your family.

It is illegal to have permanent stands on public land report it to local sheriff dept or ldwf enforcement