I,m having a slide-in built. It will be 8 foot wide plus jacks. Stock mirrors go out 1 foot from the body of the truck to the end of the mirror. It says Mc Kesh mirrors extend 20 inches. From where? Also Lucerix and Power-Vision. What are their measurements from body out. I need some in put on what will be the best set-up for 8 foot wide . Thanks