I say pretty much the same things but I also say: “If you are having guests who have not been previously booked then they must leave by 9pm”. This gives people some time to have a normal dinner with friends who came over in the afternoon to hang out but not so late that they start drinking, don’t want to leave and then getting rowdy after 11pm. I also say that music and tv must stop at 11pm. I don’t enforce these rules strictly but it is a good idea to get some stakes in the ground.
As far as them turning up with more than the booked number then you need to politely reiterate at check in how many people are booked and remind them of the rule about what time non-paying guests must leave by. Or send a text immediately afterwards to the booker with a “friendly reminder” about this. I also have a backup rule that I need to know how many people are sleeping there for the fire dept in case of an emergency.
If you really think they are staying overnight then turn up in the morning and wait for them to come out. And get AirBnB to get them to pay for the extra and give them a really bad review. Usually people tell me when they will be having guests over and I remind them that if they change their mind and want to stay overnight of the extra guest charge ($15) and the maximum number of guests that can be accommodated (4).Then again I live upstairs and they know that and I check the number of cars in the morning from my window though never been a problem so far.