Does anyone know the price USD for an additional stopover in a region with Global Explorer?

Say for example i fly back to PVD, a 1 hr drive south of Boston. And there are "maximum of two stopovers is permitted in your region of origin". 1 stop would be used in PVD, another somewhere else in USA later in the year (not going over the 29K and over the 20 flight segments) as a round trip somewhere back to (PVD-?-BOS).

Thank You