Intercostals question

[TJay]

Hey guys still building my Kitfox 1 here, was getting ready to shape the intercostals for the tail. Now I see my horizontal and elevator get them but it does not say anything for the vertical. Well I think I would like to make some for it. I believe the leading edge and trailing edge of the vertical fin is 5/8th tubing, so that needs to be the with of the plywood front and rear, now my question is in the middle how wide should I make it. Keep in mind the leading edge on my rudder is also 5/8ths and the trailing edge is 3/8ths, should I just lay a strait edge on the rudder and onto the vertical and see how far it sticks out and go with that. And one more question, if I am to do this how far back from the leading edge on the vertical do I come back before starting to taper back to the trailing edge? Hope this all makes sense.