The DriveControl mod covered everything I was wanting, except the area counter. So with some searching, I found this mod for FS13 and converted it over surprisingly easy. Along with conversion, the HUD has also been changed to match the current in-game HUD. The left indicator is total area covered by the machine and the right indicator is session area covered by the machine.
Simply place the mod in your mods folder and it will auto appear in all combines, forage harvesters (pull type included), sugar beet harvesters (pull type included), and potato harvesters (pull type included). For the pull type equipment, you must have the harvester selected, not the tractor or any other attachments.
I have tested this mod myself in single multiplayer and certify that it functions correctly with no errors.
Credits: Manuel Leithner, Gate & JDboy
LS15_ThreshingCounter (file size = 33 KB)