Mine are mounted 31 inches apart from center to center. As far as how far back is determined by the deck or layout of your boat. I use the Titelok Widow Makers individual holders they are mounted on a ball and can move forward, backward side to side or even diagonal directions. Not all folks have the same leg and arm length and they are highly adjustable. Base tracks aren't mounted yet I just got them today. Get in there and set on a bucket with your holders and find what's comfortable for you. I have a sidekick set so used that for initial testing purposes.
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