There was a case where a CO entered an ice house (Not on Mille Lacs, but in Minnesota) and busted a guy smoking crack or pot. (illegal drug bust). The guy was convicted and he appealed the case to the Minn State Supreme Court. The Court ruled in the man’s favor and tossed the conviction due to illegal search by the CO. (Entering without a search warrant)
However that ruling did not necessarily change the law and it remains on the books. (As far as I know) So, in other words, they can still enter without permission. If they did bust you with illegal drugs, you would have a pretty good case against the CO. Your case would probably get tossed out. This entire issue is a big grey area. Technically in Minnesota a CO needs a search warrant to enter your ice house or inspect your live well and count fish. You are totally in the right to refuse any search by a CO until he gets a search warrant signed by a judge. But are YOU going to be the guy who tests out the limits of the law? Probably not.
Good Luck,
-J.