I had a set of mirrors that strapped onto the fenders and they jiggled all over the place. You felt like you were drunk or somethine. I don't know what you're towing with, but I tow with a 2002 Tahoe and I've since bought a set of mirrors that slide right over my existing mirrors (no tools required, not glue, etc). They're great and do not jiggle at all. I forget where I got them, but here's a website that has them, and they're very reasonable.
http://www.autoaccessconnect.com/towingmirrors.html
Happy camping!
