Build in a tip weight box so that you can adjust the weight as needed. Changes in line length, engine offset, leadout position IF you put that ability in, prop size, many things will affect how much tip weight goes in the box. During hard inside manuevers, if you see the top side of the outboard wing, you need a little more weight. See the bottom, take a little out.

3/4 to an ounce for the average 35 size bird on 60' center 15's.