This paper explores an extension to a geometric approach of finding optimal routes for commercial formation flight. An adaption of the Breguet range equation, alongside specific aircraft characteristics, is used to represent realistic aircraft and underlying changes in weight as fuel is burnt off. Weighting schemes, for both nominal and differential rates of fuel burn, are introduced and compared. Finally a method for finding wind-optimal routes in a formation flight paradigm is developed in order to assess the effectiveness of a geometric estimate for the formation pair assignment problem. Using the geometric method to allocate formation pairs is shown to offer good performance for solutions with a significant reduction in computation time against all possible wind-optimal formation routes.