I think that it's not unreasonable for game wardens, and other officials who are preventing or investigating poaching to enter privately owned non-curtilage land for that purpose. Otherwise, all privately owned land would be open to poaching with essential impunity, and hunting/fishing laws don't only apply to public land.

A trail camera, however, is not in and of itself evidence of poaching, and officers should have zero rights to interfere with someone else's trail camera in any way. Neither should officers be allowed to set up their own trail cameras on private land (without permission from the property owner). If officers find a trail camera, they should seek to speak with its owner, either by contacting the property owner, or by leaving a business card with the camera and waiting for the owner to contact them (if they so choose).

they basically rummaged through his camera looking at all the pictures looking for evidence of hunting violations. Game wardens do this thing all the time.”

In this case, the officers confiscated the camera, downloaded the images from it (without a warrant), and only later got a warrant to review them. Nothing illegal was found.

...“Open Fields Doctrine,” which was established in a Supreme Court case called Hester v. United States. That doctrine essentially establishes that Americans don’t have privacy in “open fields,” even if it is privately owned land with posted no trespassing signs

Good luck on challenging the government and case law about open fields. In my local area, a 10ft privacy fence around an entire property was just about the only thing that made a house's curtilage extend to the property line. I was actually amazed when the court went in their favor.