Sam, I started out with a similar problem of needing too much down trim. Also my plane was a little too twichy in pitch. I solved the problem by adding a couple of washers to each rear cabane strut and readjusting the interplane struts. This gives about 1 degree of negative pitch to the upper wing with respect to the lower wing. I also added enough weight in the tail to allow the plane to fly level with neutral elevator trim. The plane flew good before I did these mods but flies much better now.

Ken