- Roof probably is a safe route but, but yes, you'd have to avoid any curtains tucked in there along the sides.
- On Hardwiring, make sure you are NOT tapped into any systems that are tied to safety OR to any electronics.
On my S60, I tapped into Power Electric Drivers Seat (if you have that) for Battery. At least on my vehicle, electric seats remain on whether car is on or off. And they were not tied to any other critical systems.
For ACC I tapped into the heated seats on my car. Again, not tied to any safety systems and only works if car is started.
I am a car owner too and have NEVER installed a camera before. But I learned via "Trial by Fire". Did have a mechanic solder and show me how to test fuses to determine proper fuse to use.
If you look back earlier in thread, you'll see we made a mistake and used a fuse (12V) that apparently was tied into other systems. So I had to move the ACC.