Sorry I haven't been posting here lately - I've moved even further out into the boondocks, and my home internet is stubbornly recalcitrant when it comes to posting here. I'm currently at a cafe.

: I'm thinking Sea Ranger or the Disko Bay Dave Gentry did with the
: same construction method. Do I have the right builder and
: design?
: Are these two designs suitable for a woman, or are they too
: narrow?

There are two issues you bring up: Cockpit size, and which is the right boat for her.

Have you tried to get her in your boat? That might be a good start. In any case, you can make the cockpit coaming larger or smaller as needed . . . .

As for the right boat, I'd say the answer is "that depends." How big is she, really? Every female yoga instructor that I know is too small for the Disko Bay (cockpit size not being taken into account). They just don't sink the boat enough and it's less stable for them than for an avg sized (or bigger) guy. My considerably narrower Yost Roldarka is much more stable for smaller paddlers - and is more than roomy enough for them (for day paddling).
IIRC, the Sea Ranger is one of Tom's bigger "narrow" boats - perhaps the Sea Rover would be a better choice?
But, all that depends on how big she is - I know a number of athletic women who are at least as big - or bigger and taller - than me. It'd be easier to help if you'd just go ask her how much she weighs! :)