I've found them to work better for me if they are located in the lower corner of the mirror right next to the van. With the mirrors set to eliminate the blind spots, see thread elseware, I am able to see the sides of the van and also see the ground right up to the bottom of the front doors. Good to make sure you're between the lines etc.
I agree with J R. I've also added a convex mirror above the rear view mirror. It attaches with a rubber strap and is fully adjsutable. Gives a great view of passengers. Found it in the baby department at the Target.
2001 LX, GG, mud guards, cargo tray, keyless remote, CD player, Blaupunkt speakers