Google will do nothing. I’ve tried for over a decade to get a fake city removed from Google Maps. I’m making the name up but imagine you have a neighborhood near you called Northfield. When google maps started someone from the neighborhood thought it would be great to make up city with the same name.
No amount of complaining will remove it. It only exists on Google maps, not on Apple Maps, Waze, Openstreet, or the various garmin/navitronics outdoor/boating navigation apps I have.
My understanding is these are called Paper Towns. Map makers add them as a way to identify when their copyright is being violated by others coping the maps wholesale.
Maybe add a sign with an admission cost and warning that rescues cost a minimum $1000?
Tell them you have two options, you call the police or they pay the posted fees and you pull them out.
Being the nice guy for the first one or two idiots is fine, but I imagine your inconvenience has a cost?