That is one beautiful tandem atmo! I have noticed that the Jack Taylor bicycles have some of the most nicely done boxlining of any out there. The lining is simple and elegant, not overwrought.

WRT the stoker's position being too tall for your wife to ride, I suggest shortened cranks. My wife is 5'4" and rides my Davidson which is 50cm c/c and the seatpost is extended by about 2 1/2 inches with a Brooks Flyer saddle. Maybe between a combination of shortened cranks, "slamming" the stoker's seatpost and using a saddle that has a lower profile like a B-17 may make the bike manageable for your wife. I'm sure you already know this but just in case you haven't thought of it before now, the stoker does not need to support the bike - stokers feet are supposed to remain on the pedals when in the saddle.