I'd go with the CIPA mirrors https://www.etrailer.com/Custom-Towing-Mirrors/CIPA/11650.html?feed=npn&gclid=EAIaIQobChMIioqj1s-51QIVlIl-Ch0N0QCkEAQYBCABEgJObvD_BwE
I had them on a Tacoma, the only problem was the mirror vibrated loose with that wing nut. Put a lock washer on it and crank it tight.
I looked around a bit for tow mirrors and found these K-Source strapons had good reviews.http://www.ksource.org/Towing-HitchingProduct.asp?Lavel=2&Category=Universal I have a pair but never put them on because I went from a 8' wide trailer to a Trailmanor 2619.
I test fitted them on the 4Runner, only two of the four clamps work, bottom of the mirror they don't go in. If I had to I could file the plastic outer mirror and the clamps so they slid in. K-Source has good ratcheting rubber straps on the backside if you can get the mirror side clamped. They have stout adjustable connections with Phillips screws.
If I still had an 8' wide trailer, I'd go with the CIPA's again. I went to a narrow trailer so I don't need tow mirrors.