Just to make it fair, there ought to be a license to hunt trophy hunters.

Nah, not kill them, unless you are a lion or an elephant or other trophy animal. Trophy animals ought to be privileged with no-limit trophy hunter hunting.

As humans we'd be allowed to hit trophy hunters with tranquilizer darts and tag their ears or something, and post their photos on the internet, as trophies.

Rather like the catch-and-release-unbarbed-hooks requirements for fishing in some places. You get to catch the fish, take the photo and brag about it, but then you release them. You can't eat them, you can't stuff them and hang them on your wall..

Nobody wants to eat trophy hunters anyways. They taste like Viagra. And their heads mounted on the wall would be damned ugly.