Hello CG,
I'm not sure I understand well what you say, but... here is my reply.

The wing tip - stab tip measurement is a good one and necessary to align the wing and stab together. Previously the wing must have been aligned with the fuse in the classic way: mount the wing in place and the measure LE from root to tip left wing and right wing, then the same for TE. Then, measure distance between wing tip and fuselage tail (i.e. where you hinge your rudder).
All these measures must be equals or must be "equalized" as close as possible (1mm tolerance is ok...). The the stab: make the above measurements and the stab is automaticalli aligned with wing and fuselage. It remains to check stab against wing for perfect aligment when seen from behind: here eye is really a precise tool! Also the Keith idea helps a lot to have a really fine tuning!

If you are still in doubt, CG take a look at this thread, where can be seen a professional builder (Mark from ZNLine!!!) making one of their planes. When I discovered it I did not sleep the night!!! All building stages are explained with pictures, wing and stab alignment included.

Here's the link:

http://www.rcuniverse.com/forum/m_53.../tm.htm#534573

Good reading!