So nobody answered the question and jumped to conclusions... The answer is it depends entirely on the law enforcement person who stops you. I have a couple game warden friends, and have posed this question: My boat is rated for 6 people. I can very easily fit 4 adults in back, and 3 kids in the bow. I am still under the weight capacity sticker, and the boat is absolutely stable. Is this legal?
2 of the 3 game wardens said they would have absolutely no problem with that, its obvious I'm under the weight limit, and as long as the boat doesn't look overloaded and the kids have life jackets on, they would wave at me and say have a nice day. The 3rd was the youngest guy, and rules are rules. Common sense doesn't apply.
Ironically, in the states that don't require capacity tickets, I would be LEGAL by removing the sticker and having 7 people on board. Technically my boat came with a couple different engine options, so the largest I/O option would be more weight than an additional kid, but the capacity sticker was common across all models.