Look at the Winstead shooting vests. They will make you a custom fit vest for I think $185? The side adjustments will allow you to adjust the fit to your liking.
Once you shoot with a vest on, it's hard to go back...LOL. To me, IMHO, you are better able to "weld" the stock to your shoulder w/o so much tension needed to simply support the rear of the rifle. You add a layer of pulse deadening between you and the rifle. They are kinda heavy witch adds to your weigh and makes you somewhat steady. Give you a place to keep up with all of your gear - Timers, Ammo, magazines, OCI, Pens, ear protection, sight setting, lens pen, score book. Heck Cathy keeps a stuffed animal in hers I think...., if you shoot high power they catch some of the recoil, give you a place to hang a towel from, give you a place for name tag, award pins, State your identy or "motto", etc.
Then for the most important reason...They make you look so damn good!
Seriously, The Winstead's do alot to support our sport and they have a top knotch product. Give him a call and he can help you with the required measurements.
Chicken George