If you're in Southern California (or in a state or city where these guys travel to), I cannot give a stronger recommendation to Calibred Customs, a very experienced and professional mobile business that specializes in Blackvue Dashcam installations for Tesla Model S and X. They have done about 300 thus far and are now increasing their business to the tune of doing 1-3 installations a day. I bought a 650S-2CH on sale and they came to my house to install it. I provided the camera, they provided everything else. You can ask them to provide the camera with memory card as well.
In a matter of 90 minutes, Johnny and Darius had installed the cameras flawlessly. Not only this, but they also took the time to set up my WiFi (naming it Melania, after our car) and set up the mobile app on my phone and showed me exactly how to configure and use it. My car was spotless once they were done -- it looks like a factory install from inside and out. On top of that, they were courteous, professional, on time, didn't nickel and dime me on anything, and offered to come back in person if I ever had any issues. Amazing. I was not paid or given a discount for writing this review. I can't imagine doing this work myself -- many things can go wrong and my time is worth more (so is the car!). Johnny's cell is 310-654-0532. Tell him "Melania" sent you.