I bought those mirrors and they worked fine on my way 2002 F-150. It had oval mirrors.
When I bought a 2011 F-150 with larger square mirrors, they would vibrant off. With the use of double backed sticky tape and small bungee cords I used them another year, until I could afford factory type pull out towing mirrors.
It was a semi-permanent installation but I towed with them for over 8000 miles. I believe the pair cost under $50.00 while the F-150 towing mirrors were over $200.00 each on Amazon.
As always, there is nothing wrong with a spit and bailing wire approach if it works and you are not sure what you want to do for a final solution.