as Ian says it is setup on boot, because when logging into the APRS servers the position is given.
For Rebroadcast purposes the most important thing is the GEOID, because this is used by FLARM for altitude
so getting this wrong means that altitudes are broadcast incorrectly
can I ask a more fundamental question - why do you need to move the groundstations ?
the bigger issue I guess is for the MLAT feed if you are capturing that to go back to 360Radar ?
thx
Lee