Hi,
I don't like the elastic-band type mounting options for the seat post from Garmin so I bought these 3D printed brackets off eBay and they do a great job of mounting right under the saddle.
It uses a GoPro style interface so can be used for other things as well.
I guess if you always use a saddle bag then this wouldn't be for you, but I prefer not to ride with one.
It's just a really neat option...I wish Garmin would offer something like this out of the box!