How to wire a backup camera?

[JamesInSJ]

2015 X5d...didn't realize it didn't have a backup camera by default and PO didn't option that. So wwhile ago I bought the appropriate module and camera/switch replacement, but never got around to doing it because it requires running the wire from the inside of the lower gate all the way up to the back of the dashboard. I think I'll be fine once I get it up to the dashboard area, but how the heck is everyone routing a wire from the trunk area up to the dash? In other cars I've been able to route along flooring or floor rails, but seems like the standard wiring in the X5 goes somewhere along the roof.

Anybody have any guides? Experience they can share? I didn't find anything on Youtube, just references to running it along the roof but I don't see how to manage that.