The "normal" rear dashcam mount involves going through a very thight cable holder which is very difficult to reach and go through.

This solution involves 3D printing a very simple piece that will be stuck under the rubber seal. There are numerous videos on YouTube showning the basics of a dashcam install for a Tesla Model X. With this install, you can fit the cable under the trim panels all the way to the back, no need to fish it through.

Prefer to print on ABS over PLA, as it has better heat resilience. If you print on PLA and leave your can under the sun, the heat may deform the mount to the point the adhesive can't stick on it anymore and the dashcam may fall.

Here is what the piece looks like:

The idea is too fit the cable underneath the lock, so the piece is stuck with even more strength.

From the inside, the camera is even more concealed than with the "normal" install.