I'm semi-retiring my Protektor rear bag for the SEB Bigfoot and wondering what's common with ear spacing? I know it's probably personal with lots of shooters, but what's more common with F-Class/Benchrest type set-ups? Rifle stock butt end is 3/4" at the bottom and tapers out and up. I'm thinking 1/2", but 3/8" and 5/8" are options. Thanks