Don't use the FS09 map. The ideal solution would be to have av charts for the area you are flying but road maps make a halfway decent substitute, presuming there are recognizable landmarks along your route. FS09 models large landmarks fairly accurately, even to the shape of lakes. The thing it does not do well is model roads but that can be overcome. I flew a 241 mile dead reckoning flight from Galveston to New Orleans this morning and it worked quite well using a AAA US road map.
My understanding of dead reckoning would preclude the use of GPS (or VOR's) as suggested above. Dead reckoning is navigation from one place to another using a compass, timer, and map or chart. It is a necessary and useful skill in real world flying since depending on VOR's or GPS can be dangerous if your receivers go out or if there is trouble with the station you are depending on. Careful pilots remain aware of their positions, regardless of what electronic aids they use.
To do it, you plot your course, estimate your times between identifiable landmarks along your course, and then fly from one landmark to the next, correcting for wind drift, until you reach your destination. To do it well, use a hand computer to calculate actual ground speed and correct Est Time Enroute for the next legs based an actual rather than estimated speed. I use a fairly large Aerodyne C1 Flight Computer because it is easier to use and read quickly in flight but any handheld that will allow you to convert time and distance to spped will work.