Realize that at some point, when you have gotten the aero bars comfortable, they're effectiveness is reduced because your upper body isn't streamlined. Lowering the upper body to be level with the ground as much as possible, is one of the things that improves your aerodynamics.
There can be a happy medium. The bar design is one issue, stem height another, body flexibility is part of it, but at some point you just need to get used to keeping your head raised.
FWIW, there was a RAAM competitor a few years ago (Race Across AMerica) that used a bungie cord from the back of his helmet to his butt to take the strain off his neck muscles.
Last edited by Steve B.; 02-15-14 at 06:26 PM.