Hi Jake,
You have your logic just backwards. The more mechanical advantage between the car and jib clew, the further out the car positions itself. This is because for a given jib leech tension, sail shape, there is less tension in the jib sheet. The force that tends to center the jib traveller car is the sideways to boat center line component of the tension in the jib sheet on the leg between the car and the jib tack. As the jib sheet tension goes down for a given jib leech tension (because of higher car to clew mechanical advantage), the further outboard the jib car will position itself.
Bill