I've played about a book and a half of this AP so far so I'm not sure how this idea would fit into the latter books. Our party discussed not being law enforcement but eventually decided to run it as is.

One idea that I thought was cool would to have the party be a hard-boiled detective agency, who gets jobs from Edgewatch and other divisions. Could be doubly good if your party has entrepreneurial inclinations. You still get some of that office drama flavor and the restriction of following the law and a neat explanation as to why the players rarely have access to other personnel. The patrolling the festival section doesn't last long and you could just have the events happen while on their way to the office and the zoo a report while they're at the office.