OK, I think I got some good pictures here. First a simple one of the adapter from the top, looking on it as you would normally see it. Anyone with the full mount installed will note that I have not used the side guides because I have a silicone case on my phone and the guides do not allow for the slight extra thickness of the phone with the case, even though it's only an extra few millimeters thick.
I then closed the "top/lid" to this area (which is the back part of the picture above, that supports the back of the phone) and managed to get my phone down in the big storage area looking back at the adapter and mount. I haven't really seen a picture with this perspective but I think it does a good job showing it in place. Note that the top of this picture is now the horizontal bottom of the "cover". I realize that's a bit confusing but hopefully gives some more context for this perspective.
Now I'm just going to crop to the adapter itself to make a few points....
This picture better shows 2 things. First, note how I had to use the Dremel to shave down the plug itself so it would fit through the hole in the mount. I think most anyone would figure out that needed to be done. With some previous attempts with other plugs I was trying to use a knife to whittle down the plug but it was almost impossible to get a precise cut as needed. I then went to a hand file and after several minutes of minimal progress I remembered that I had a Dremel. If you don't have a Dremel, I still recommend a file over a knife so that you can get a nice, tight fit.
The more important thing to note is the support which is holding up the plug, preventing the phone from pushing it back down through the mount. In this picture you can see the two "wings" which are supporting the lower edges of the plug. This piece is held in place by the screw.
With the normal Tesla USB plugs with the right-angle connectors, this piece (with the two "wings") is normally oriented at a 45 degree angle compared to what I have here. This piece is normally oriented such that one of the wings completely covers the back of the right-angle plug. In my picture, one of those wings would normally be pointing straight at the camera while the cable would be entirely below it, going straight to the side.
The way I angled that piece is not ideal, and if you use too much force you can definitely break it. If I really wiggled the plug from the bottom (cable end), it would not remain below the two "wings". However, fortunately the phone cannot wiggle the plug from the top because the side-to-side movement is severely restricted thanks to my Dremel shaving that holds it in the hole of the mount.
Having said all that, Tesla, if you're listening, please offer some other right-angle plugs that fit the mount. There aren't so many different plugs that you can't get some company to make different variations for all of us. At least give the spec to a third-party and let them sell them. I'd gladly have paid too much for a cable that fit perfectly to avoid going through this process.