Surprise wedding

Hi! My boyfriend and I have been discussing a courthouse wedding no ceremony. We are having problems agreeing on the route we want to go. I personally do not want my family to attend, I have never been close to my parents. My boyfriend on the other hand wants his parents, sisters and grandparents to attend. We can't invite his but not mine, a little part of it is because I also do not want them either. I want to take a day off work go sign the papers and then announce our marriage by having a party. I want to keep everything a secret. The problem is not only we can't agree on our family but also I still want him to pick out a ring and do the whole proposal. Keeping that a secret would be very hard especially for my boyfriend, almost impossible. I suggested pretending like we are going to go through with the traditional wedding, but the Saturday of our "engagement party" we come dressed in our wedding attire and announce to everyone it is not an engagement party, it is actually a reception and we got married the day before at the courthouse privately. I am looking for ideas and opinions about it, my boyfriend is a little wary on how to keep the entire thing a secret from everybody but also planning an entire reception with the help of my MIL who also won't know (boyfriends request to have her involved). We are aware our family's are going to be upset but our final decision is our wedding, money, time, and lives not theirs, we are going to let them be upset and understand it, but setting boundaries.