There was a big discussion on here last year about limits and the net result was that after you catch your limit you have to stop fishing for that species. For example, after 6 walleyes reduced to possession, you have to fish for perch, sheephead, bass, etc., anything but walleye. After 6 in possession you can't cull and sort-throw back smaller ones in possession and keep bigger ones to stay at the limit. You can't hand your pole to someone else after hooking a fish you suspect is an over limit. You have to release it. Once you hook a fish it is yours. Also you are correct in that there is no boat limit, only individual limits. I personally don't like it but that is the law.
(And certainly don't advertise an over limit situation in an open forum.)