Looking at those I do not like the idea that they obscure your main mirror even though you have the extended one. I still regard my main car mirror as the main one to use and the towing mirror supplementing my vision for safety. However it seems you have no choice in your case.
That was my thinking too before I got them. With the Milenco, the extra mirror is just an extension. I used to notice that due to the nature of the attachment (on the arm) the milenco mirror would vibrate a little and the resulting image was not clear. The main mirror would be checking for traffic along side, and the extension for checking behind.
With the suck-it-and-see, there is no vibration (perhaps because of the silicone mount?) and image is super clear. Also - the extension mirror is in exactly the same plane as the car mirror. The there is no change of angle from one to the other. And actually, there is a surprising amount of car mirror left. The marketing picture is a pretty poor install! I attached a picture of mine here. They are in storage in the caravan, or I would do a picture from in the car.