I am retired LEO. It is a myth that game wardens/conservation officers have more authority than other cops. They do not. They all are subject to limitations set forth in the U.S. Constitution which guards the citizenry against unreasonable search and seizure. The fact that many believe they have such power might cause some officers to act illegally. I hope not. They are trained professionals and know what their job is as well as the limitations. They MUST have probable cause to search, to open your cooler or uncover items concealed from their view. That said, perhaps their probable cause is less than you think. Don't forget they must show that PC in court in order to obtain a conviction. Blood, fish scales, hair, etc in your truck bed, on a tarp or cooler or your hands or clothes is sufficient. ALWAYS comply. Don't argue. Never tell them what the law is or how your rights disallow his actions. That will not deter him and it may encourage him to look further. Cooperation is always best. You will have plenty of opportunity to challenge his actions later.