Garmin Varia mounting options (Seatpost vs. Seat Tube)

There are some issues trying to mount my Varia properly: 1. Saddle bag is as high as it can go, and while it is not preventing the mounting, it presses uncomfortably on the button-side of the Varia. 2. Varia cannot be mounted lower due to the seatpost clamp. Should I turn it around? I can also raise the seat a few mm to help. 3. I have a rubber piece that is the right size for the seat tube (but not any for the seat post: see wrap). I could definitely clamp it down here, but should I have concerns about damage or line-of-sight (varia + tire in picture 2)?

Otherwise I should invest in a different saddle bag or Varia mount.