Don't know where you are at, but public duck hunting lands out here are 25 hp max (well some of those lands are 25 max). Lots of speed freaks run 40's with 25 stickers. A few 50's and 60's with 25 stickers. Fish and game people have gotten smart about it, though. I was out testing a customer's boat (50 hp on a boat that was rated for 40). Just pulled into the launch area, boat still on the trailer. Fish and wildlife guy walks over and says howdy, wants to know if I have a boat registration and insurance. I said no, it's not mine, belongs to a customer...so he checks it out to make sure it's "safe" and "legal". Mind you all I was going to do was dunk it in the water, still on the trailer to test run it-and nothing more. He looked at the capacity tag and noticed it said 40 max hp. He looks at me and says this boat is over powered and technically is a felony, and advises that I not test it. So I left and went up the road to a creek that nobody knows about, dunked it and went back to the shop. 5 minute deal.
Then-one of the VERY few times I went to the public waterfowl hunting areas, took a friend's boat. 1542 DuraCraft with a 40 hp Tohatsu with 25 stickers. Hunted from daylight until about 8:30, headed back to the ramp and got checked. All licenses were good but he mentioned that the 40 hp motor was not "legal" on a boat that is rated for 25hp. My buddy mentioned that it was a 25 hp motor. Guy looked at the tag on the clamp and knew it was a 40. Then my buddy said that the clamp was replaced with one from a 40, and the guy's response was that he knew it was a 40 by looking at it. Said he knows guys are doing that and in doing so, is a felony and punishable by jail and or prison time. But he let us off with a verbal warning.
2 times it's happened...didn't get a ticket but I would probably be mindful of what the officers are looking for. 99.9% of the time you'll be fine. There is the ONE officer who wants to go by the book and he's the 0.1% that you have to worry about!