In my quest to expand my knowlage of mounting and wiring solutions for dash cams I signed up to the DashcamTalk forum [well worth it]

And I found this interesting, regards providing a feed to a front facing cam, but could be used also for rear mounted cams. As it does away with you having to actually switch the power on via a socket power converter, or trailing the power converter cable from the front of the passenger side fuse box. It will apparently give you circa 30 minutes parked up dash cam footage. [front and rear if using two cams, nice] Possibly need to upgrade the fuse for the interior curtisy lamps using two cams, not looked into it that deep yet, just found it.

its on page two post number 30

Quote the post

I'm not very happy with the position as the Mobius is more visible than
the 808 #16 which was in the same postion but a little bit higher.
However it' not very obvious if you don't look very attentively, so for
the moment I'll stick with it.

The camera is powered from the "permanent" + of the interior lamp, which
actually is cut off after 20-40 minutes since locking the car. This way
I have about half an hour of front parking cam.

Its a good idea to use that permalive feed if you have the cables. Sadly some cables like mine are a 12v connection only, and because they operate on USB they dont always have just positive and negative, so it makes guessing a bit more difficult!