Replace “As a Daily Action, the GPS may create and append to the list of Stops a new Stop with a Name of their choice, a Capacity of 1, and no Type. In doing so, the GPS may also increase the Capacity of a randomly chosen Stop by 1.” with:-

If every Tripper (ignoring those at a Starting Point; unless all Trippers are at a Starting Point) has fewer than 13 Stops after their Location, the GPS should create and append to the list of Stops a new Stop with a Name of their choice, a Capacity of DICE3, and a random Type from among those named in the rule “Stop Effects”.