On the longer rods that I build, if I feel there is going to be a concern over it being tip heavy, I usually will ask the client what reel he plans on using and then I will match the weight of the intended reel with one that I have of similiar weight(size of the reel doesn't matter, just the weight) I then mock up the build with all guides and hardware for it. If it is definitely tip heavy I will then start adding bullet weights inside the rear of the blank until I feel that it has acheived a more balanced state. After I am satisfied, I then remove the weights, add epoxy to them and re-install. I have also added a plug in the blank at the appropriate length, put the weights in and put a drop of superglue on the last one to necessitate removal in the event of a future reel change varying in weight.