what model rifle are you doing, maybe you can just get a wooden stock, (many times used one's can be found for certain rifles, or cheap wood stock in general) )and keep in mind that just trimming the butt of the stock, doesn';t help small hands at all with the distance from pistol grip to trigger , which is also where many smaller shooters have issue's!
that said, on SYN stocks, I have known a few guys that did mod's to them and filled them with fiberglass, like used in auto body repair's to build inside of hollow stocks up, so things could handle recoil and such, allowing you to shape things as you like too, from both end of stocks, to cheek rise adjustments!