How did you wire up your rear facing dash cam?

I got my front dash cam wired up thanks to a nice diy with photos on here, thank you very much!

Now I'm wanting to wire up a rear facing cam, and wanted to see if anyone had photos and instructions from their install, as the plastic around the brake light is pretty tight, and I don't want to scratch up the plastic opening it from the bottom side, or risk scratching or cracking the hatch glass prying from that side.

Which wire do you tap, is the brake light wire always live or is there another wire up there that is on with the ignition?

Thanks!