When I was training to be a driver for UPS they taught us 5 "rules" that help in my everyday driving...

1 and 4 offer far more coverage, and should be taught in lieu of the "traditional" orientation. Height is not the issue here, it's horizontal angle that's up for debate. Angle them a bit downward, if you'd like.

Could have been a little clearer in the graphic, but basically, "Make your mirrors look like figures 1, 3 and 4. Figures 2 and 5 leave too much blindspot"