I had a similar problem and installed some "tabs" on the butt plate that keeps it aligned with the kidney plate. My butt plate tended to be too wide on the hips and flared out more than it rode up. But this solution should work for you. I used scrap plastic from my kit. Painted the outside black. CA glued them in place.
I hope that helps.
Oh, and for the shins, long industrial velcro and a hidden snap secure them perfectly. Easy solution. Mine used to pop open all the time. Not now!
