Looks like the mothership has developed an OEM source mount for your GPS also...here is the link and a pic.
https://www.yamaha-motor.eu/uk/accessories/genuine-options/functional/gps-stay-fjr/1MC-GPSMT-00-10/details.acc?overviewhash=%23%2Fexplore%2F363270%2F0|363328|FJR1300A|0%2F|
https://www.yamaha-motor.eu/uk/accessories/genuine-options/functional/gps-stay-fjr/1MC-GPSMT-00-10/details.acc?overviewhash=%23%2Fexplore%2F363270%2F0|363328|FJR1300A|0%2F|