I have the Tow-N-See. They are good.
You can get them flat or convex, get BOTH convex.
On the Highlander you can stick them on the bottom or edge of the HL mirror, and you still have a good portion of the mirror that's usable. You can adjust the HL mirror accordingly without really affecting the Tow-N-See's adjustment if they are convex.
They don't shake, I've never lost one, the only thing is occasionally large vehicles going the opposite direction sometimes create a big air draft that tends to push on the Tow-N-See and mess the HL's mirror adjustment. Not a big issue, but due to this I would look at Milenco's. Otherwise the Tow-N-See are good.
Pictures snapped a couple years ago, towing the popup: