My first strategy would be to go for placing the extender itself in a nice central location for coverage to your phones

Where should I place my extender?The thing is, the ideal location to get a GPS lock may not be the ideal place for best coverage of the areas important to you

If accurate *location* info is important to you then a used extender registered in someone else's name may not work for you

You can also access a GPS signal strength meter to help find the ideal location for the GPS antenna