It was important for me and my mom to have my marriage officially recognized in the Catholic church, so my FI and I are planning on getting married the day before we leave (we're meeting with my priest Friday to officially set it). We're just having our parents, siblings, and grandparents who can't travel attend.
We're definitely keeping it on the down-low, but I don't like lying if someone asks me outright about it so I usually just explain what we're doing, but since most of our Catholic friends know that you can't get married outside the church, I feel like a lot more people are going to end up knowing than I'd like. I really hope no one feels like they're wasting their time going all the way to Cancun when it's not even our "real" wedding, even though, for us, it WILL be our real wedding. It's all pretty stressful!