Got it. Will keep you posted. I will start by hardcoding the physical location of the 2 GPS antennas on the vehicle so my code will be far from a straight merge.
In my case the 2 antennas are on the longitudinal centerline of the vehicle, one (“Primary”) at the rotational center of the vehicle, i.e. between the 2 wheels, and the other approximately 1.1m forward of it. This means that the GPS position of the primary GPS is what I will use as the GPS position of the vehicle. When the rover rotates, this antenna does not move. I have found this to be important to get pivot turns to work. The secondary GPS is just used for heading…
I expect that others may choose different geometries, in particular, 2 GPSs at the same fore/aft station, one left and one right of the centerline. This geometry would require calculations to determine the position of the center of the vehicle.
Hence I think I should leave it up to others more familiar with ardu-code to figure out the appropriate parameter names & values/encoding necessary to parameter-ize the different scenarios of the positioning of the 2 antennas.