Good day and welcome!
Permanence of the point of interest is part of the acceptance criteria:
Must be a permanent physical, tangible, and identifiable place or object, or object that placemarks an area
A clear and established outdoor recreational sites have been clarified as acceptable — needing a visual focal point if an artificial sign is not present. That is the rec area itself is being submitted and is permanent.
However, the actual review process may prove difficult for these types of nominations. The decision may hinge with the proof you can add in the supporting details that it is really what you claim it is.
You can put a mock up of the submission here if you want.