One issue with new tiles is that the current mission cards would not specify the new tiles in the pickup or destination locations. One idea I had was to make two sector tiles with "wild" mission locations. You cannot pick up mission cards at these locations. However one can be used as an alternate pickup(or start) location and the other could be an alternate end location. You could not use both an alternate start and end "wild" location to accomplish a mission. You would also recalculate the payout (if relevant) based on the new distance you are flying.