When we retired late 2001, my DH was 55 and I was 47. We spent the winter in a 55+ park in central FL because my in-laws lived there full time. The owners required at least one person to be 55 and they take copies of driver's license every couple of years as proof. But they also bend the rules if need be. Across the street from us, that winter, was a couple in their late 60's who had their daughter and grandkids (around 8 - 10 years old) staying with them because of a physical abuse situation with the husband/father until the daughter could get back on her feet. As long as the kids behaved themselves, there was not a problem with the office. And the kids WERE well behaved. Not everyone in the park knew of the situation and there was talk, but the owners of the park knew this was a special situation. I have also heard that even though parks may list themselves as 55+, they really can't discriminate against age, that a small percentage of people can be under 55. Of course, this is not an "official" statement, just talk. I also would suggest you give any parks you are considering staying at a call first and ask if your "young" age of 53 would be a problem.
And I have to agree with others about "older" residents and activities; sometimes being somewhere with residents too much older isn't any fun. In 2001 the medium age in the park was close to 80 so the activities and dances reflected their music. Now that most of the older residents have moved on, and their "kids" (mid 60's) have moved in, the music has changed, we now have more people our age to hang with, similar interests, etc. it's more fun and I can't wait to get there in the fall! Do some research and phone calls - and most of all, have fun!