I leave my OEM mirrors adjusted as driving without the trailer........I gotta lean forward a bit to see the truck bed. That allows me to keep them fairly far out to see vehicles beside of me. I also have small convex mirrors in the upper outside edges.
The CIPA mirrors are adjusted so I can see most of the sides of the trailer, including the tires in the lower part of the mirror. Seeing the sides of the trailer allow me to see how close I am to guardrails, trees, tunnel walls, etc, and viewing the tires to make sure I clear obstacles. I also use the CIPA mirrors for most of my backing.
Used together, the outside CIPA and outside OEM mirrors give me a pretty good view of things, since the inside rear view mirror is useless unless it is just for checking if the trailer is still back there.
Chap , DW Joy, and Fur Baby Sango
2006 Ford F150 Super Cab 4x4
2008 Surveyor 263