There is something I had never considered for towing mirrors and factory extendable mirrors such as these:
https://www.amazon.com/Genuine-Toyot.../dp/B01DA7X8KS
With my McKesh mirrors, they extend out very far so I can see the same point 200 feet behind the trailer. (This is a legal requirement in at least some states.) Besides that, having my regular mirrors and towing mirrors allows
(a) me to keep the stock mirrors in the original position so I can see what is
beside my truck
(b) me to adjust the towing mirrors separately so I can see that point 200 feet behind the trailer.
If you use factory extendable mirrors, you will lose the ability to see what is immediately beside your truck. If you have a vehicle that you missed coming up on your right side and is now sitting in your blind spot, you could miss it completely with the factory extendable mirrors because they are directed farther out to see behind the trailer. I have had on occasion seen something in the Tahoe mirror that was not visible on the towing mirror. And don't forget, modern trucks and SUVs have more blind spots than ever before. I used to drive a full sized Mercury Grand Marquis. It had to go in for service for a week because some one hit me broadside. They gave us a Toyota Corolla as a loaner. That car was so bad for visibility out the back, even my wife who hates driving big cars said my Mercury was easier to drive than that Toyota. That says something.
Anyway, having two sets of mirrors (factory and towing) has a huge advantage that I never considered before. Sure, strap on towing mirrors don't look fashionable, but for me safety is first.