This app was mentioned in 2 comments, with an average of 2.50 upvotes
https://play.google.com/store/apps/details?id=net.tadteam.halfmilepct&hl=en
It will show your exact mile marker and distances to future locations, but won't put a dot on the map for you.
https://play.google.com/store/apps/details?id=com.ruffworkllc.android.pcthyoh&hl=en
That app will cache weather reports, water reports and Halfmile maps for you.
It's still listed in the Android app store but hasn't been updated for years. https://play.google.com/store/apps/details?id=net.tadteam.halfmilepct