I only have these hard rules, that I alert you of ahead of time.
-No Shoes
I have a dedicated cheap towel for the hot dock problem. They stand on the towel and take their shoes off. The upholstery is the main concern, hence no shoes on the boat.
-At your own risk, and Follow All instructions
Ahead of time I warn them with the worst that has happened and that this is not risk free. (Jelly Fish Sting, Fish? bite (Something bit her...still don't know what it was), Broken leg from jumping in the water without listening to my clear instruction that there are only 2 ft of water under the boat, all have happened on my watch...)
Also, for their safety, they must follow my instructions right away, always. There's a reason that I'm happy to explain, but it may need to wait a moment before I can, depending on urgency)
Of note, but not a rule I give ahead of time
-Suspicious foods only on the swim deck. (Too colorful/too small)
-I don't have any friends that drink enough to be a problem, so this has never been an issue that I had to worry about. I would hope unless it's a gorgeous specimen drinking to get liquid courage to give me something extraordinary (which is not happening, as I'm married and alcohol makes my wife sleepy) I would expect folks to remain sober enough to safely walk off the boat unassisted, and NOT throw up in the boat.
-I don't take their money. They'll eventually treat me to something that evens it out. I was going to spend almost the same anyway.