No Smoking

We are having our ceremony and reception in a park where no smoking is allowed. Unfortunately, not all of our guests are non-smokers. I have two questions:

1. How do we get the word out that people cannot smoke? (The park ranger was adamant that we restrain people from smoking.)

2. What do we do if people (I believe inevitably) ignore the rule - or forget or whatever - and smoke anyway?

Any ideas would be greatly appreciated!