Why did you "have" to put your dogs on your friends site?
Why did you not complain to park staff?
I think I would have politely talked to them and voiced your concerns. Possibly mentioning that it might be better not to cross over your site, it would upset the dogs. Also about the grease, again politely inform them you were not appreciative of grease in your fire pit. Again explain how it encourages your dogs and other animals to expect food there. If they became rude then have the attendants take care of the issue. Sometimes people need to be educated and how nice it could have been for you to be the teacher.