You have a good paper map that you hand out to guests and campers. How about posting the map AT the lake so it’s easy to see?

Here’s an example at Trillium Lake in Oregon. It’s simply put the map behind plastic on a sign. Or, to match you other signage on the property, you might make something more permanent.

Do you have any locations (trails, lakes, rivers, vistas, etc.) that you can give a sense of place by adding a sign?