I was thinking about that myself in the same location. The only thing negatively that I can think of is that the cell phone Will most likely be in direct sunlight. I’ve had many occasions where the phone goes into overheat mode.
I got this Wireless charger last year - it clamps onto the phone automatically when it's placed in the cradle, and releases with a button press. Worked slick and keeps it within line of sight - for $30 it's worth it to keep the phone secure when burning around the lake at 50
It's just a sticky suction cup - has never once moved unless I actually detached it on purpose. One note - don't attach to the soft-touch parts of your dash - the suction cup will leave a small dimple (that eventually fades out under the sun). Right next to the SIMRAD was my best spot.