I felt compelled to reply since I am one of those construction worker types.
I'm an engineer that gets sent all over the country to start up new power plants, and my wife and I will find a nice park and stay for 3-6 months. We have never been asked to maintain our area. The park has always taken care of it. Your's is the first mention I have ever heard. I usually work 7 days a week, so would not have time to devote to this, and I would probably find the whole thing strange. Isn't grounds keeping part of the space rent?