This app was mentioned in 2 comments, with an average of 0.50 upvotes
Check out http://caltopo.com/map.html#ll=38.8,-98.4&z=5&b=t and this app(https://play.google.com/store/apps/details?id=com.gammonapps.android.straightlinenavigator&hl=en) to get grid coordinates for specific locations.
Land Nave Assistant! Used it during EIB, works like a charm.