Not true at all. Mine is mounted at the top center of the rear windscreen, which is recommended. Yes, you must run the cable from under the headliner to the hatch. There are two ways to do this:
1: Run on the passenger side all the way to the back of the roof under the headliner: easy. Then pop the grommet tube that connects the electrics from the car to the hatch. Takes a bit of fiddling. Be gentle. The driver side grommet is too full of cables, so you must use the passenger side. Then snake through the top of the hatch to the center. Takes some work, but no more than 30 minutes, if you have experience, which I would hope the installer does. That is the cleanest install. Absolutely nothing is visible. If your installer does not know how to do that, find somebody else. It doesn't take much knowledge to do. I have read posts where people have done some crazy runs all along the hatch, from the top down and all the way around. Not necessary at all. There is room to snake the cable through the welded panels to exactly where you want. Not really not hard at all. A little patience and gentle touch is all that is needed. Two people helps a lot, but I have done it alone.
2: Jump the gap from the headliner to the hatch on the pass. side, tuck the cable in under the top of the plastic hatch trim, snake to the cam and you are done. That's about 15 minutes, max.
I have done both. I had to replace my cable because I was too rough the first go around and crimped it. That's why I say be gentle. I spoke to the dealer and he was great. He warned me that the cable is unusually fragile. Both the cable itself and the ridiculously small center prong that plugs into the camera. It likes to coil and doesn't like to straighten and can crimp very easily. So the second time I did a temp install of jumping the gap. Honestly, I can't see the jump at all with the hatch closed and I have to look for it when it is open. I'll do #1 when I have time.
I strongly suggest that you do not mount the cam to the your headliner. It will: look terrible, be subject to being bumped and jostled, leave a permanent mark on the headliner and, most importantly, give you significantly less resolution to the rear cam footage, which could be the most important cam for hit and runs. And you have inclement weather. The farther the cam is from the glass, the less it can see, by a huge margin. Kind of like how sound degrades at the square of the distance, if that makes sense.
Honestly, this is one of the easiest installs I have ever done and I am an ametuer, not a professional. I used to do HiFi installs as a kid 45 years ago on my cars. That's about it. Aside from getting the cable through the grommet to the hatch, the rest of the install took no more than 45 minutes in total. The hatch, because of fiddling and patience, took about an hour with figuring out how to do it for the first time.
If you have Al & Ed's in SLC, go to them. They will know exactly what to do. You should see their radar install. It is a true work of art.
I hope this helps. Don't let them gouge you.
