I have the same brand of mirrors that you have listed on your original post. I used them on a previous model chevy that used the same mirrors that you listed. I am now on a second pair that fits my 2008 chevy.
I love them. There is zero shaking, vibration, etc. With them on, I can see completely down both sides of my SV-291 (which should be 8 ft wide), and I too keep them angled down so I can see tires on both sides.
And I love being able to pull them off for the other 345 days of the year i don't camp.
Sorry they aren't working out for you... I suggest you ebay them if you change.
Nights camped in 2010 = 21 nights
2008 Chevy CCab 5.3L 4WD Z71
2008 FR Surveyor 291
Slpybear, Mrs Slpybear, Three Cubs