+1 for the magic marine footstraps... best footstrap out tehre. they are hard to locate in the U.S. I have a few sets coming in soon if you want to drop me a note.
No need for backing plates and mount the footstrap as far back as you can, there is no where else to put it. You need your crew as far back as they can go. Some of the newer boats are designed with a chine on the back corner which works perfect for mounting the footstrap.