Max Vehicle Length for Campgrounds

I have noticed that many campground (Fl State Parks in particular) have a maximum vehicle length listed for many of the sites. I have never noticed this or paid any attention to this since we have camped for 20+ years with a Coleman tent camper which was only 18 feet when fully extended. Can anyone give me some guidance as to what the max length is referring to. I'm now the proud owner of a 2001 3023 using a 2000 Dodge 1500 Ram Van as a tow vehicle.


Thanks

Woody