You can buy brass spinner nuts that help with a tail heavy plane. A friend of mine just finished building a Sig Something Extra and it was tail heavy when he was done. He tried a brass nut, but it still was not enough. He ended up turning a new spinner nut out of brass that was a little bigger than the one he bought and it worked great. Balanced the plane perfectly, and since out in front of the prop is the longest lever arm you are going to get out in the front of the plane, it was less weight than if he was to put it somewhere else.