Minn - How much wieght is to much to add? What's the most you've put in the tail to get it to balance?
ORIGINAL: MinnFlyer
I usually just stick weights to the bottom of the fuse just forward of the tail wheel.
Another option is to cut a hole in the bottom of the fuse, Epoxy the weight in place, and then cover the hole with covering.
If you're feeling ambitious, you can make a hatch there for future access.