That's a great help, a couple of different options, those will help with the synchronization. I don't have to update the GPS constantly, once every ten seconds or so, it doesn't go that fast so it doesn't travel to far.
Calling it "Controlling the Servo" may be a bit misleading. You're right the servo library does most of the work. My controller has 2 thumb joysticks, speed and steering, I read them in and map the analog in value to the servo angle. I then send the servo angle over to the rover and it does the rest.
I'm going to work on this, I hope you don't mind if I have any further question I get in touch with you. You've been a tremendous help. Not sure where you are, I'm in the Boston area, if your ever around I owe you a drink.
Thanks again
John