This is a good idea! 
You know your people, and you know a few of them will assume you know they are going to your wedding and don't even care to RSVP, maybe they forgot or maybe they don't even know if they could make it and get there last minute without notifying. I have seen it all, believe me. 
Would you consider to have an extra table for those "Wedding Crashers"? 😄 

Say YES! to Puerto Rico for your Destination Wedding.