That's a good idea chevman. And, if you have a wood router, the backer board can be given an attractive edge, then stain, and polyurathane it to match the handrail. If the backer is Teak, then it's even easier, because all you need is some teak oil to match them both. Small pieces of teak might be a little harder to find. May try a large marine dealer.
Another option would be cypress. Much easier to find small pieces.
Good luck, and please post a picture of the finished product.
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