Some of the best ones I've come up with would require either a
: two-tone, scarfed sheer strip on the hull (not desirable due to weakness
: of strip, esp. since I have loads of full-length WRC strips available), or
: nice long strips crossing from the deck to the hull.

You don't need to worry about strength, as any scarf that is made well (or even just not terribly) will have the same strength as the wood, esp. when coverd with fiberglass. remember that these boats get their strength from the fiberglass, the wood is just there to space it out do we can fully utilize it. But... I can see your not wanting to waste the full length strips.