JumpingBean,
Add a couple of pennies and see if the outboard wing drops if you support it by the fuselage center. If you really want accuracy you will need to keep that weight box accessible.
The difference in flying between Dacron and wire is more drag than weight. The wire has much less drag.
Beware of lots of engine and rudder offset. This will cause more pull sometimes but when the power cuts, what do you do then. The ideal situation IMHO is to have little or no offset on either. Remember you are already pulling on the plane when it tries to fly straight.
Good luck with it.

George