I still am hoping to get this project going as soon as work permits.
I had a change of philosophy and decided to buy a high quality (and expensive) mirror with a backup camera monitor built in.
This is the camera I bought:
I'm not sure if I will end up putting this in myself or if I'll have a shop do it. I'm planning on getting a remote starter and windshield tint strip installed soon and might see what they would charge to wire up the mirror and camera.
If I do it, I am thinking of running the video wire above the headliner and will post pictures of the project.
BTW, the Crosstrek mirror attaches with a standard wedge mount.