SooprmanX,. You have some valid points and if you own the place or have control of what goes on there then any rule that comes from you should be respected by any and all guests.
It's sad but don't assume that other people have common sense and think the way you do. Sounds as if the guy with the dog doesn't seem to care. You are the steward and have the right to make the rules but others people that come on it need to know your wishes/rules and that includes family member too. Make it clear to all concerned. All to often I hear of others not respecting the land owner and /or lease rules and it makes it worse on everybody involved. On small properties the problems you stated can be magnified compared with a larger one
You shouldn't have to draw up contract or agreement but many do. Have visitors/guest acknowledge that the agree with the rules set forth and the consequences if not followed. It may seem that you appear to be a "Ahole" but it's the smart thing to do protecting what is yours.