best advice I can give you is, if your gps is capable, download(purchase) a birdseye imagery subscription(unlimited downloads for 1 calender year) and use it to mark the spot.
What I always do is scout on google maps, find the location I want and then download the location in my gps and mark the spot using my gps and not rely on something else. When you can see the terrain on your gps you can mark spots in the exact location you're looking at on google maps.
If you need any further assistance, please let me know.