Overcoming a Garmin GPS Bug in the Previous Example

The Linux10 Picnic site at Sunnyvale Baylands Park has the 122.0 degree longitude meridian running right through it.
Either my Garmin GPS or the version of gpstrans that I use has a bug that "snaps" coordinates within a half mile from the east onto the meridian.
Here's the raw plot for the previous map.

The solution was just to get a road map, take the image into GIMP and edit it so it looked "close enough".
That works if you're writing directions to a picnic.
It's not good for precision applications.