I've not ran across any that couldn't be cut down. Putting the pad back on is the only trick with some. Most of the better stocks are designed with enough extra material to allow for a certain amount of cutting. The cheaper tupperware stocks are really not designed to do so. But a block of wood cut to a tight fit and epoxied into the end gives something to screw into.
Filling the hollow stock with expanding foam, letting it harden and cutting excess off will give a flat surface where the pad can be epoxied directly to the stock. Cutting a $1.99 flip flop to the correct size and gluing it on works great BTW. Saves a lot of money and weight. The last one I did weighed 1/2 oz vs 5 oz for a standard pad and cost under $2.